"Although... there is not yet extant a body of Inductive Logic, scientifically constructed; the materials for its construction exist, widely scattered, but abundant: and the selection and arrangement of those materials is a task with which intellects of the highest order, possessed of the necessary acquirements, have at length consented to occupy themselves. Within a few years three writers, profoundly versed in every branch of physical science, and not unaccustomed to carry their speculations into still higher regions of knowledge, have made attempts, of unequal but all of very great merit, towards the creation of a Philosophy of Induction: Sir John Herschel, in his [A Preliminary] Discourse on the Study of Natural Philosophy; Mr. Whewell, in his History and Philosophy of the Inductive Sciences; and, greatest of all, M. Auguste Comte, in his Cours de Philosophic Positive, a work which only requires to be better known, to place its author in the very highest class of European thinkers. That the present writer does not consider any of these philosophers, or even all of them together, to have entirely accomplished this important work, is implied in his attempting to contribute something further towards its achievement..."