KAXT HAS XOT ANSWERED HUME. 543 means " (he continues). "An object may be contiguous and prior to another, without being considered as its cause. There is also a necessary connexion to be taken into considera- tion ... I turn the object on all sides in order to discover the nature of this necessary connexion, and find the impres- sion or impressions from which its idea may be derived. "_JEii_ is a "question concerning the nature of that necessary connexion which enters into our ideas of cause and effect ". In that -ige of his Ussat/s, too, where it would seem to Reid, Gregory, and pretty well to Hamilton also, that Hume is asleep (aliquando bonus dorm it at Humiu.s, see Reid's WorJts, pp. 79 and 83), Hume is in reality perfectly wide-awake, and is only asking them, though a little involvedly rather, indeed, challenging them, them and anybody else, to explain the necessity. This, then, is the angle of the inquiry ; and surely now once for all, in all plainness. Let us next see equally plainly what it was that occasioned to Hume nay, that stifl occa- sions to us the difficulty of an answer. This difficulty lies in the materials in which the law of causality presents itself. These materials are always matters of fact ; and matters of fact are, simply as matters of fact, incompetent to necessity: they never transcend probability. Or, as we may say it otherwise, the law of causality presents itself always in the objects of experience, and objects of experience are never equal to necessity. Experience itself is always inadequate to necessity ; it always falls short of it. As an example of the presence of necessity, and of a necessity which we can see into, understand, and satisfy oui'selves about, there are the so-called relations of ideas. It is on such relations that all the sciences connected with quantity, as geometry, arithmetic, &c., are founded. We do not require to take the thing in hand, and actually finger the fact, to find out what is the state of the case with it we require simply to be told that 2 and 2 are 4, that 3 fives are 15, &c., in order to see into the truth, and the necessary truth, of what is said. Similarly, we simply see that a straight line between any two points must be there the shortest pos- sible ; or that parallel lines, being parallel and that means always equally distant the one from the other can never meet, let them be continued even into infinity ; or that the angles at the base of an isosceles triangle are equal, the one to the other ; the three angles of any triangle equal to two right angles ; the square of the hypotenuse of any right- angled triangle equal to the squares of the sides, &c., &c. All these truths depend on relations of ideas, and these are
