The method of approach to detailed criticism of prose-writers and poets adopted by Dionysius is in a large measure comparative. The procedure of comparison is threefold: firstly, the bringing together of passages from authors to elicit points of resemblance or of difference between their styles secondly, the assumption of the existence of common critical standards for all works of art, whether literature, painting, or sculpture thirdly, the use of metaphor and simile to illustrate matters of criticism which need the assistance of some visual or mental image to make clear the exact meaning of the point of criticism. The metaphorical vocabulary is the richer for the greater preoccupation of Dionysius with aesthetic appreciation than with philosophical analysis; and any seeming differences in technical vocabulary are compensated by the freedom with which his vocabulary in general draws on the Greek of his own and earlier times. The following list gives some of the more interesting metaphorical expressions used in the rhetorical works, with notes on their meaning and, in some cases, with illustrations of the use of the same or similar terms in other Greek critics and in the volumes of scholia.