Editor's notes; Introduction; Obituary notices by Sir Frederic Bartlett, F. R. S.; Part I. Analytical and Causal treatments of Perception (Epilogue from the PhD Thesis): Part II. The Mechanism of Human Action: 1. Introductory; 2. Principles of automatic regulation and servo-mechanisms; 3. Review of synthetic principles and their application to living systems; 4. Brain mechanisms: levels; 5. Cyclical action in men and machinery; 6. On human behaviour; Part III. Experimental Work: 7. Anderson Stuart's Contrast phenomenon; 8. Brightness, discrimination, borders, and subjective brightness; 9. On the effects of looking at the sun; 10. Localized aniseikonia following 'eclipse blindness'; 11. Correspondence regarding amblyopia; 12. The photochemical stimulation of the optic nerve; 13. Theories on dark-adaptation; 14. Introspections on learning the Link Trainer by a mixed visual and instrument method; Part IV. Sensory Quantification: 15. Crawford's results in binocular summation (unpublished); 16. Measurability of sensation; 17. In defence of the measurability of sensation-intensity; 18. Quantitative estimates of sensory events; 19. On the question of sensation scales; Part V. Aspects of Psychology: 20. Lectures on psychology for medical students; 21. The nature of animal behaviour; 22. Laws of association; 23. Psychological effects of the black-out; Part VI. Philosophy: 24. The nature of explanation - reply to critics; 25. Causes and purposes; 26. Man's extension of himself; 27. On the working of the mind; 28. On the inductive study of language and the meaning of particular words; 29. Induction, coherence, relational systems, and the objective validity of thought, 30. Life; 31. Claustrophobia; 32. 'The Marxist Philosophy and the Sciences'; 33. Disagreement; 34. War as a part of life; 35. Songs of creation; Bibliography of the writings of K. J. W. Craik; References.