"He studies nature with a full faith in the uniformity of her laws, and in the certainty that truth may be ascertained by diligent labor. It is truth only he loves; not anxious to build up a system, nor pretending to explain every thing, he says to his pupils, such and such have been my observations; you can observe as well as I, if you will study the art of observation, and if you will come to it with an honest mind, and be faithful in noting all which you discover, and not merely the things which are interesting at the moment, or those which support a favorite dogma; I state to you the laws of nature as they appear to me; if true, your observations will confirm them; if not true, they will refute them; I shall be content if only the truth be ascertained."