He was a man who was not easily satisfied with his attempts to arrange the order and proportions of his plans for mastering that new world of unknown truth, which he held to be within the grasp of man if he would only dare to seize it; and he was much given to vary the shape of his work, and to try experiments in composition and even style.

He wrote and rewrote.
Besides what was finally published, there remains a larger quantity of work which never reached the stage of publication.

He repeated over and over again the same thoughts, the same images and characteristic sayings.

Among these papers is one which sums up his convictions about the work before him, and the vocation to which he had been called in respect of it.

It is in the form of a "Proem" to a treatise on the _Interpretation of Nature_.