XLVII

Among Prerogative Instances I will put in the twenty-third place Instances of Quantity, which (borrowing a term from medicine) I also call Doses of Nature. These are they which measure virtues according to the quantity of the bodies in which they subsist and show how far the mode of the virtue depends upon the quantity of the body. And first there are certain virtues which subsist only in a cosmical quantity, that is, such a quantity as has consent with the configuration and fabric of the universe. The earth for instance stands fast; its parts fall. The waters in seas ebb and flow; but not in rivers, except through the sea coming up. Secondly, almost all particular virtues act according to the greater or less quantity of the body. Large quantities of water corrupt slowly, small ones quickly. Wine and beer ripen and become fit to drink much more quickly in bottles than in casks. If an herb be steeped in a large quantity of liquid, infusion takes place rather than impregnation; if in a small, impregnation rather than infusion. Thus in its effect on the human body a bath is one thing, a slight sprinkling another. Light dews, again, never fall in the air but are dispersed and incorporated with it. And in breathing on precious stones you may see the slight moisture instantly dissolved, like a cloud scattered by the wind. Once more, a piece of a magnet does not draw so much iron as the whole magnet. On the other hand there are virtues in which smallness of quantity has more effect, as in piercing, a sharp point pierces more quickly than a blunt one; a pointed diamond cuts glass, and the like.

But we must not stay here among indefinites, but proceed to inquire what proportion the quantity of a body bears to the mode of its virtue. For it would be natural to believe that the one was equal to the other; so that if a bullet of an ounce weight falls to the ground in a given time, a bullet of two ounces ought to fall twice as quickly, which is not the fact. Nor do the same proportions hold in all kinds of virtues, but widely different. These measures, therefore, must be sought from experiment, and not from likelihood or conjecture.

Lastly, in all investigation of nature the quantity of body — the dose, as it were — required to produce any effect must be set down, and cautions as to the too little and too much be interspersed.