From these things we may observe, (and it will further show this our natural and original need of being improved by discipline,) how it comes to pass, that creatures made upright, fall; and how those who preserve their uprightness, raise themselves by so doing, to a more secure state of virtue. To say that the former is accounted for by the nature of liberty, is to say no more, than that an event’s actually happening is accounted for by a mere possibility of its happening. But it seems distinctly conceivable from the very nature of particular affections or propensions. For, suppose creatures intended for such a particular state of life, for which such propensions were necessary: suppose them endued with such propensions, together with moral understanding, as well including a practical sense of virtue as a speculative perception of it; and that all these several principles, both natural and moral, forming an inward constitution of mind, were in the most exact proportion possible; _i.e._ in a proportion the most exactly adapted to their intended state of life; such creatures would be made upright, or finitely perfect. Now particular propensions, from their very nature, must be felt, the objects of them being present; though they cannot be gratified at all, or not with the allowance of the moral principle. If they can be gratified without its allowance, or by contradicting it, then they must be conceived to have some tendency, in how low a degree soever, yet some tendency, to induce persons to such forbidden gratification. This tendency, in some one particular propension, may be increased, by the greater frequency of occasions naturally exciting it, than of occasions exciting others. The least voluntary indulgence in forbidden circumstances,[99] though but in thought, will increase this wrong tendency; and may increase it further, till, peculiar conjunctures perhaps conspiring, it becomes effect; and danger of deviating from right, ends in actual deviation from it; a danger necessarily arising from the very nature of propension, and which therefore could not have been prevented, though it might have been escaped, or got innocently through. The case would be, as if we were to suppose a straight path marked out for a person, in which a certain degree of attention would keep him steady: but if he would not attend, in this degree, any one of a thousand objects, catching his eye, might lead him out of it.