derived from analogy, it is the resemblance only, which is affected.  Without some degree of resemblance, as well as union, it is impossible there can be any reasoning:  but as this resemblance admits of many different degrees, the reasoning becomes proportionably more or less firm and certain.  An experiment loses of its force, when transferred to instances, which are not exactly resembling; though it is evident it may still retain as much as may be the foundation of probability, as long as there is any resemblance remaining.

SECT.  XIII.  OF UNPHILOSOPHICAL PROBABILITY.

All these kinds of probability are received by philosophers, and allowed to be reasonable foundations of belief and opinion.  But there are others, that are derived from the same principles, though they have not had the good fortune to obtain the same sanction.  The first probability of this kind may be accounted for thus.  The diminution of the union, and of the resemblance, as above explained, diminishes the facility of the transition, and by that means weakens the evidence; and we may farther observe, that the same diminution of the evidence will follow from a diminution of the impression, and from the shading of those colours, under which it appears to the memory or senses.  The argument, which we found on any matter of fact we remember, is more or less convincing according as the fact is recent or remote; and though the difference in these degrees of evidence be not received by philosophy as solid and legitimate; because in that case an argument must have a different force to day, from what it shall have a month hence; yet notwithstanding the opposition of philosophy, it is certain, this circumstance has a considerable influence on the understanding, and secretly changes the authority of the same argument, according to the different times, in which it is proposed to us.  A greater force and vivacity in the impression naturally conveys a greater to the related idea; and it is on the degrees of force and vivacity, that the belief depends, according to the foregoing system.

There is a second difference, which we may frequently observe in our degrees of belief and assurance, and which never fails to take place, though disclaimed by philosophers.  An experiment, that is recent and fresh in the memory, affects us more than one that is in some measure obliterated; and has a superior influence on the judgment, as well as on the passions.  A lively impression produces more assurance than a faint one; because it has more original force to communicate to the related idea, which thereby acquires a greater force and vivacity.  A recent observation has a like effect; because the custom and transition is there more entire, and preserves better the original force in the communication.  Thus a drunkard, who has seen his companion die of a debauch, is struck with that instance for some time, and dreads a like accident for himself:  But as the memory of it decays away by degrees, his former security returns, and the danger seems less certain and real.