Yoga Vasistha , a is a philosophical text attributed to Maharishi Valmiki, although the real author is Vasistha. 

Chapter 21 to 24 of Yoga Vasistha Explains Out of Body experiences 

Chapter 21: the Practice of Meditation, Astral Travel. 

Saraswati continues speaking to Leela:— 

1 Soon after death occasions the lack of physical senses, the sight of the world appears to the soul as if he were seeing it with open eyes when he was living.

 2 Before him is presented the circle of the sky and its sides with the cycle of its seasons and times. He is shown the deeds of his pious and mundane acts, as if they were to continue to eternity. 

3 Objects never before seen or thought of also offer themselves to his view, like the sight of his own death in a dream, as if they were the prints in his memory.

 4 But the infinity of objects appearing in the empty sphere of the non-physical intellect is mere illusion, and the baseless city of the world, like a castle in the sky, is only the creation of imagination. 

5 Memory of the past world makes it known to us. Therefore, the length of a kalpa age and the shortness of a moment are only false impressions proceeding from the speed and slowness of our thoughts. 

6 Therefore knowledge based upon previous memories or otherwise is of two kinds, and things known without their cause are attributed to Divine Intelligence. 

7 We are also conscious of thoughts that we have not thought of before in our minds, such as we often have in our dreams. Another may remind us of our deceased parents, so we think of them.

8 Sometimes genius supersedes the province of memory, as in the first creation or discovery of a thing, which afterwards is continued by its memory. 

9 According to some, those visible worlds are said to have remained in their ideal state in the Divine Mind. According to others, there were no pre-existent notions of these in the mind of God. 

10 According to some others, the world manifested itself not from memory but by the power and will of God. Still others maintain it to be the production of a sudden, fortuitous combination of intelligence and atomic principles (kakataliya sanyoga). 

11 Completely forgetting the world is called liberation. That cannot be had if consciousness is attached to what is desirable or is averse to the undesirable. 

12 It is difficult to effect an entire negation of both one’s subjective and objective knowledge of his self and the existence of the outer world. Yet nobody can be freed without the obliteration of both. 

13 As the fallacy of taking a rope for a snake is not removed until the meaning of the word snake is known to be inapplicable to the rope, so no one can have rest and peace of mind unless he is convinced of the illusory nature of the world. 

14 Even with that, a person who is at peace with himself cannot be wholly at rest without divine knowledge because, even though he has rid himself of the devil of worldliness, the ghost of his inner ignorance may overtake him. 

15 The world is certainly a monster in itself without the knowledge of its Author, but the difficulty of knowing the First Cause has rendered it an impassable wilderness. 

16 Leela said, “If memories are the cause of one’s reincarnation, then, O goddess, tell me what were the causes of the birth of the brahmin couple, without the vestiges of their past memories? 

17 The goddess replied:— Know that Brahma the first progenitor of mankind, who was absolute in himself, did not retain anyvestige of his past memories in him. 

18 The first born, who had nothing to remember of a prior birth, was born in the lotus with his own intelligence (chaitanya) and not because of his memory. 

19 The Lord of Creatures being thus born by chance of his own genius or creative power, and without any assignable cause or design on his part, reflected within himself, “Now I am become another and the source of creation.” 

20 Whatever is born of itself is like a nothing that was never produced at all, but remains as the absolute intellect itself in the clouds (chinnabhas). 

21 The Supreme Being is the sole cause of both types of memories (those caused by vestiges of prior impressions, and those produced by prior desires). Both conditions of cause and effect are combined in Him in the sphere of his consciousness. 

22 Therefore our tranquility can only come from knowing that cause and effect are the same and that the auxiliary cause is in Him. 

23 Cause and effect are mere empty words of no significance because it is the recognition of the Universal Consciousness that constitutes true wisdom. 

24 Nothing seen in the physical world or known in the mental or spiritual worlds is ever produced. Everything exists within the consciousness of one’s own soul. 

25 Leela said, “What a wonderful sight you have shown me, O goddess. It is as auspicious as morning light and as brilliant as lightning. 

26 Now goddess, please satisfy my curiosity until I become thoroughly familiar with this knowledge through my intense application and study. 

27 Kindly take me to that that mountainous place where the brahmin couple, Vasishta and Arundhati, lived and show me their house.” 

28 The goddess replied:— If you want to see that sight, you have to be immaculate. You must give up your personality and your ego-sense and attain awareness of the unintelligible Consciousness within the soul. 

29 Then you will find yourself in an empty atmosphere situated in the sky that resembles the prospects of earthly men and the apartments of the firmament (i.e., nothing). 

30 In this state we shall be able to see them (the field of another’s imagination) with all their possessions and without any obstruction. Otherwise this body is a great barrier in the way of spiritual vision. 

31 Leela said, “Tell me kindly, O goddess, the reason why do we not see the other world with these eyes, or go there with these our bodies.” 

32 The goddess replied:— The reason is that you take the true future as false, and you believe the untrue present as true. These worlds that are formless appear to your eyes as having forms, just like you see the form of a ring when its substance is gold. 

33 Gold, though fashioned into a circle, has no curve in it. The spirit of God appearing in the form of the world is not the world itself. 

34 The world is an emptiness full with the spirit of God. Whatever is visible is like dust appearing to fly over the sea. 

35 The ultimate substance of the world is all a false illusion. The true reality is the subjective Brahma alone. Our guides in Vedanta philosophy and the conviction of our consciousness are evidence of this truth. The believer in Brahma sees Brahma alone and no other anywhere. He looks to Brahma through Brahma himself, as the creator and preserver of all, and whose nature includes all other attributes in itself. 

37 Brahma is known not only as the author of His work of the creation of worlds, but as existent of himself without any causation or auxiliary causation. 38 The practice of meditation trains you to disregard all duality and variety and to rely only on one unity. Until you are trained through your practice of meditation, you are barred from viewing Brahma in his true light. 

39 By constant practice of meditation, we become settled in this belief of unity, and we rest in the Supreme Spirit. 

40 Then we find our bodies to be an aerial substance that mixes with the air, and at last, with these our mortal frames, we are able to come to the sight of Brahma. 

41 Being endowed with pure, enlightened and spiritual frames (astral or subtle bodies), like those of Brahma and the gods, the holy saints are placed in some part of the divine essence. 

42 Without the practice of meditation, you cannot approach God with your mortal frame. A soul sullied by physical sensation can never see the image of God. 

43 It is impossible for one to arrive at another’s castle in the sky, when he is unable to see the castle in the sky that he himself imagined. 

44 Therefore, give up your gross body and assume your light intellectual frame. Immerse yourself in the practice of yoga so that you may see God face to face. 

45 It is possible to labor and build castles in the air. In the same way, it is possible through the practice of yoga, and in no other way, to behold God, either with this body or without it. 

46 Ever since the creation of this world (by the will of Brahma), there have been false conceptions of its existence. It has been attributed to an eternal fate, niyati (by fatalists), and to an illusory power, maya shakti (of Maya vadis).

 47 Leela asked, “O goddess, you said that we both shall go to the abode of the brahmin couple, but I ask you, how is that possible? 

48 I am able to go there with the pure essence of my sentient soul. But tell me, how will you who are pure intellect (chetas) go to that place?” 

49 The goddess replied:— I tell you lady, Divine Will is an aerial tree and its fruits are as unsubstantial as air, having no figure or form or substance to them. 

50 Whatever is formed by the will of God from the pure essence of His intelligent nature is only a likeness of Himself and bears little difference from its original. 

51 My body is the same and I need not lay it aside. I find that place with my body like a breeze finds odors. 

52 As water mixes with water, fire with fire, and air with air, so does this spiritual body easily join with any material form that it likes. 

53 But a physical body cannot mix with an non-physical substance, nor can a solid rock become the same as the idea of a hill. 

54 Your body has its mental and spiritual parts. It has become physical because of its habitual tendency towards the physical. 

55 Your physical body becomes spiritual (ativahika) by leaning towards spirituality, as in your sleep, your protracted meditation, and your unconsciousness to fancies and reveries. 

56 Your spiritual nature will return to your body when your earthly desires are lessened and curbed within the mind. 

57 Leela said, “Say goddess, what happens to the spiritual body after it has attained its compactnessby constant practice of yoga? Does it becomes indestructible or does it perish like all other finite bodies?” 

58 The goddess replied:— Anything that exists is perishable and, of course, liable to death. But how can something die that is nothing and is imperishable in its nature? 

59 Again, once we realize the mistake of thinking a rope to be a snake, the snake disappears of itself and no one mistakes the rope anymore. 

60 Thus, as the true knowledge of the rope removes the false conception of the snake in it, so the recognition of the spiritual body dispels the misconception of its materiality. 

61 All imagery is at an end when there is no image at all, just like the art of carving statues must cease if there is no more stone. 

62 We clearly see our bodies as full of the spirit of God. Your gross understanding keeps you from seeing this. 

63 In the beginning, when consciousness (chit) is engrossed with the imagination of the mind, it loses sight of the One. 

64 Leela asked, “But how can imagination trace out anything in that unity in which the divisions of time and space and all things are lost in an undistinguishable mass?” 

65 The goddess replied:— Like the bracelet in gold, waves in water, the show of truth in dreams, and the appearance of castles in the sky 

66 all vanish upon an accurate perception, so the imaginary attributes of the unpredictable God are all nothing whatever. 

67 Just like there is no dust in the sky, no attribute or partial property can be ascribed to God whose nature is indivisible and unimaginable, who is an unborn unity, tranquil and all-pervading.

68 Whatever shines about us is the pure light of that Being who scatters His luster all around like a transcendental gem. 

69 Leela said, “If it is so at all times, then tell me, O goddess, how did we happen to fall into the error of attributing duality and diversity to His nature?” 

70 The goddess replied:— It was your ignorance that for so long has led you to error. The natural bane of mankind is the absence of reasoning, and it requires remedying by your attending to reason. 

71 When reason takes the place of ignorance, in a moment it introduces the light of knowledge in the soul instead of its former darkness. 

72 As reason advances, your ignorance and your bondage to prejudice are put to flight. Then you have an unobstructed liberation and pure understanding in this world. 

73 As long as you remained without reasoning on this subject, you were either sleeping or wandering in error. 

74 Now your reason and liberation are awakened and the seeds for the suppression of your desires are sown in your heart. 

75 At first, the nature of this physical world was neither apparent to you nor you to it. How long will you reside in it and what other desires have you here? 

76 Withdraw your mind from its thoughts of the viewer, the visible, and the vision of this world. Settle your mind on the idea of the entire negation of all existence. Fix your meditation solely upon the Supreme Being and sit in a state of unalterable unconsciousness. 

77 When the seed of renunciation has taken root and germinated in your heart, the sprouts of your likes and dislikes will be destroyed of themselves. 

78 Then the impression of the world will be utterly effaced from the mind and an unshaken anesthesia willovertake you all at once. 

79 Remaining entranced in your abstract meditation, in process of time you will have a soul as luminous as a star in the clear sky of heaven, free from the links of all causes and their effects for evermore