XXIX

Among Prerogative Instances I will put in the eighth place Deviating Instances, that is, errors, vagaries, and prodigies of nature, wherein nature deviates and turns aside from her ordinary course. Errors of nature differ from singular instances in this, that the latter are prodigies of species, the former of individuals. Their use is pretty nearly the same, for they correct the erroneous impressions suggested to the understanding by ordinary phenomena, and reveal common forms. For in these also we are not to desist from inquiry until the cause of the deviation is discovered. This cause, however, does not rise properly to any form, but simply to the latent process that leads to the form. For he that knows the ways of nature will more easily observe her deviations; and on the other hand he that knows her deviations will more accurately describe her ways.

They differ in this also from singular instances, that they give much more help to practice and the operative part. For to produce new species would be very difficult, but to vary known species and thereby produce many rare and unusual results is less difficult. Now it is an easy passage from miracles of nature to miracles of art. For if nature be once detected in her deviation, and the reason thereof made evident, there will be little difficulty in leading her back by art to the point whither she strayed by accident; and that not only in one case, but also in others. For errors on one side point out and open the way to errors and deflections on all sides. Under this head there is no need of examples, they are so plentiful. For we have to make a collection or particular natural history of all prodigies and monstrous births of nature; of everything in short that is in nature new, rare, and unusual. This must be done, however, with the strictest scrutiny, that fidelity may be ensured. Now those things are to be chiefly suspected which depend in any way on religion, as the prodigies of Livy, and those not less which are found in writers on natural magic or alchemy, and men of that sort, who are a kind of suitors and lovers of fables. But whatever is admitted must be drawn from grave and credible history and trustworthy reports.