To explain the influence of comparison upon the mind, I have chosen the simplest case, that of two animals of the same kind, differing in size only, seen for the first time. To complete the theory, other circumstances must be taken in. And the next supposition I shall make, is where both animals, separately familiar to the spectator, are brought together for the first time. In this case, the effect of magnifying and diminishing, will be found remarkably greater than in that first mentioned. And the reason will appear upon analyzing the operation. The first thing we feel is surprise, occasioned by the uncommon difference of two creatures of the same species. We are next sensible, that the one appears less, the other larger, than they did formerly. This new circumstance is a second cause of surprise, and augments it so as to make us imagine a still greater opposition betwixt the animals, than if we had formed no notion of them beforehand.
I shall confine myself to one other supposition, That the spectator was acquainted beforehand with one of the animals only, the lapdog for example. This new circumstance will vary the effect. Instead of widening the natural difference by enlarging in appearance the one animal and diminishing the other in proportion, the whole apparent alteration will rest upon the lapdog. The surprise to find it less than judged to be formerly, will draw the whole attention of the mind upon it; and this surprise will be gratified, by conceiving it to be of the most diminutive size possible. The mastiff in the mean time is quite neglected. I am able to illustrate this effect by a very familiar example. Take a piece of paper or linen reckoned to be a good white, and compare it with something of the same kind that is a pure white. The judgement we formed of the first object is instantly varied; and the surprise occasioned by finding it not so white as was thought, produceth a hasty conviction that it is much less white than it is in reality. Withdrawing now the pure white, and putting in its place a deep black, the surprise occasioned by this new circumstance carries our thought to the other extreme, and we now conceive the original object to be a pure white. Thus experience forces us to acknowledge, that our emotions have an influence even upon our eye-sight. This experiment leads to a general observation, That whatever is found more strange or beautiful than was expected, is judged to be more strange or beautiful than it is in reality. Hence it is a common artifice, to depreciate beforehand what we wish to make a figure in the eyes of others.