This is a kindred defect to that absence of method which has been already taken notice of. A fixed nomenclature is a beacon against repetition and discursiveness. But the Treatise has no pretension to be a work of which he who omits paying attention to any part, thereby drops a link in a chain, the loss of which will make the whole appear broken and inconsistent. There are, it is true, places where the essential parts of the author's philosophy are developed, the omission of which would render that which follows hard to be understood, but in general each department of the work is intelligible in itself. Its author appears to have composed it in separate fragments; holding in view, while he was writing each part, the general principle of his theory, but not taking it for granted that the reader is so far master of that principle, as not to require it to be generally explained in connexion with the particular matter under consideration. He seems indeed rather desirous to dwell on it, as something that the reader may have seen in the earlier part of the work, but may have neglected to keep in his mind while he reads the other parts. Perhaps the true model of every philosophical work is to be found in the usual systems of geometry, where, whatever is once proposed and proved, is held a fixed part of knowledge, and is never repeated; but as far as psychological reasoning is from the certainty of geometrical, so distant perhaps, will ever be the precision of its method from that of geometry.