In single instances we only see sequence of loose events which are conjoined and never connected, 58; the idea of necessary connexion only arises from a number of similar instances, and the only difference between such a number and a single instance is that the former produces a habit of expecting the usual attendant, 59, 61. This customary transition is the impression from which we form the idea of necessary connexion. E. _Reasoning from effect to cause and conversely_, 105-115 (v. _Providence_). In arguing from effect to cause we must not infer more qualities in the cause than are required to produce the effect, nor reason backwards from an inferred cause to new effects, 105-8; we can reason back from cause to new effects in the case of human acts by analogy which rests on previous knowledge, 111-2; when the effect is entirely singular and does not belong to any species we cannot infer its cause at all, 115. F. _Definitions of Cause_, 60 (cf. 74 n). Ceremonies 41. Chance ignorance of causes, 46; has no existence, 74 (v. _Cause_ B). Cicero 4. Circle in reasoning, 30. Clarke 37 n. Colour peculiarity of ideas of, 16. Contiguity 19, 42. Contradiction the test of demonstration, 132. Contrariety 19 n. Contrary of matter of fact always possible, 21, 132. Creation 132 n. Criticism 132. Cudworth 57 n, 158 n. Custom when strongest conceals itself, 24; an ultimate principle of all conclusions from experience, 36, 127; and belief, 39-45; gives rise to inferences of animals, 84. Definition only applicable to complex ideas, 49; need of, 131; of cause, 60. Demonstrative opp. intuitive, 20; reasoning, 30; confined to quantity and number, 131; impossible to demonstrate a fact since no negation of a fact can involve a contradiction, 132. Descartes 57 n.; his universal doubt antecedent to study if strictly taken is incurable, since even from an indubitable first principle no advance can be made except by the faculties which we doubt, 116; his appeal to the veracity of God is useless, 120 (v. _Scepticism_, 116-132). Design argument from, 105 f. (v. _Providence_). Divisibility of mathematical and physical points, 124. Doubt Cartesian, 116, 120 (v. _Scepticism_ A). Epictetus 34. Epicurean philosophy, defence of, 102-15; denial of providence and future state is harmless, 104 (v. _Providence_). Euclid truths in, do not depend on existence of circles or triangles, 20. Evidence moral and natural, 70; value of human, 82-9 (v. _Miracles_). Evil doctrine of necessity either makes God the cause of evil or denies existence of evil as regards the whole, 78-81. Existence external and perception, 118-9 (v. _Scepticism_, B, 116-32). Ex nihilo nihil 132 n.