There is no desire more natural than the desire for knowledge. We try all the ways that can lead us to it. When reason fails us, we use experience--
Experience, by example led,
By varied trials art has bred
--which is a weaker and less dignified means. But truth is so great a thing that we must not disdain any medium that will lead us to it. Reason has so many shapes that we know not which to lay hold of; experience has no fewer. The inference that we try to draw from the resemblance of events is uncertain, because they are always dissimilar: there is no quality so universal in this aspect of things as diversity and variety.
Both the Greeks and the Latins, and we ourselves, use eggs for the most express example of similarity. However, there have been men, and notably one at Delphi, who recognized marks of difference between eggs, so that he never took one for another; and although there were many hens, he could tell which one the egg came from.
Dissimilarity necessarily intrudes into our works; no art can attain similarity. Neither Perrozet nor any other can smooth and whiten the backs of his cards so carefully that some gamesters will not distinguish them simply by seeing them slip through another man's hands. Resemblance does not make things so much alike as difference makes them