3  Slip into pronounced beginning (4)

 6  Out of blue, pieces realigned and reused to make isolated sphere of experience (6)

11 Place famous for statue that's reaching out in timeless, arresting display (3)

12 Landscape's principally good about hinting mysteriously at atmospheric phenomenon (9)

13 Tetris piece: a U- or T-shaped symbol (3)

14 At first, strain clumsily to get crafty one (7)

15 Squint oddly at laser's source of light (7)

17 Essay is half poetry (3)

18 Rocky old sea turtle is forgetful dreamer on an island (5-5)

21 Could solution be obscure? (5)

23 Screenshot elevator sequence (the game's last resort?) (5)

24 Introductions to science, literature, epistemology, empiricism, philosophy, and rest (5)

25 Fiery movie with Burke's final circle (10)

26 Experienced route runners initially make a mistake (3)

30 Chaotically drew in energy for substance of Feynman's whole universe? (3,4)

32 In the evening, hard one to get: a mysterious figure (7)

34 Visualize solution's first eye-opening error (3)

35 How to solve every Witness puzzle on an iPad? (3-6)

36 Cause odd indication for what to do next (3)

37 Acts dramatically amid remote shipwreck (6)

38 With no directions, repeat complicated section (4)

39 Elements of triangle enigma elicit joy (4)

 1  Puzzling master "gets" flower (6)

 2  Knowledge based on observation from one behind me (1,10)

 4  Heraldic white man bearing augmented reality (6)

 5  Ultimately, town (the gauntlet) measures gains (4)

 6  Correct silly flubs with great satisfaction (10)

 7  Bad start, for example, and top players have no lead—amateurs! (9)

 8  Note the shape on a machine (5)

 9  Give substance to error becoming a burst of brilliance (5)

10 An unspecificied amount of hesitation in audio log—it comes before "The Fall" (6)

16 At home in swamp or traveling around the island, for instance (7)

19 Unorthodox about nothing after storyteller's second of speculation (11)

20 Stands outside holding stringed instrument with vacant expression cast up, concerning those who grind (10)

22 Peer into nameless but unopened box (4,2,3)

25 Rest of shady trees area (6)

27 Pries curiously around seabed, at last finds many-limbed creature (6)

28 Desert feature's small and satisfactory (5)

29 Slow down; I am deep, unusual (6)

31 Made red liquid escape (5)

33 Light up panels, mountain, and lake, primarily (4)