As our present head represents the very pith and marrow of the art of study, we may dwell a little longer on the process of changing the form of an author, whether by condensing, expanding, varying the expression, altering the order, selecting, and rejecting,--or by any other known device. Worst of all is change for the mere sake of change; it is simply better than literal copying. But, to rise above it, needs a sense of FORM already attained. According as this sense is developed, the exercise of altering or amending is more and more profitable. Consequently, there should be an express application of the mind to the attainment of form; and particular works pre-eminent for that quality should be sought out and read. "Form" is doubtless a wide word, and comprises both the logical or pervading method of a work, and the expression or dress throughout. Method by itself can be soonest acquired because it turns on a small number of points; language is a multifarious acquirement, and can hardly be forced, although it will come eventually by due application. [EXAMPLE FROM PRACTICE OF MEDICINE.] To show what is meant by learning Form, with a view to the more effectual study of subject-matter, I will take the example of a work on the Practice of Medicine; in which the idea is to describe Diseases _seriatim_, with their treatment or cures. At the present day, this subject possesses method or form: there is a systematic classification of diseased processes and diseases; also, a regular plan of setting forth the specific marks of each disease, its diagnosis, and, finally, its remedies. There are more and less perfect models of the methodical element; while there are differences among authors in the fulness of the detailed information. There is, besides, a Logic of Medicine, representing the absolute form, in a kind of logical synopsis, by which it is more easily comprehended in the first instance: not to mention the general body of the Logic of the Inductive Sciences, of which medicine is one. Now, undoubtedly, the best work to begin with--the Text-book-in-chief--would be one where Form is in its highest perfection; the amount of matter being of less consequence. In a subject of great complication, and vast detail, the student cannot too soon get possession of the best method or form of arrangement. When a work of this character is before him, he is to read and re-read it, till the form becomes strongly apparent; he is to compare one part with another, to see how the author adheres to his own pervading method; he should, if possible, make a synopsis of the plan in itself, disentangling it from the applications, for greater clearness. The scheme of a medical work, for example, comprises the Classification of Diseases, the parting off of Diseased Processes---Fever, Inflammation, &c.--from Diseases properly so called; the modes of defining Disease; the separation of defining marks, from predications, and so on: all involved in a strict Logic of Disease.