The Da Vinci Notebooks at sacred-texts.com
If you wish to draw a figure or any other object to look 24 braccia high you must do it in this way. First, on the surface m r draw half the man you wish to represent; then the other half; then put on the vault m n [the rest of] the figure spoken of above; first set out the vertical plane on the floor of a room of the same shape as the wall with the coved part on which you are to paint your figure. Then, behind it, draw a figure set out in profile of whatever size you please, and draw lines from it to the point f and, as these lines cut m n on the vertical plane, so will the figure come on the wall, of which the vertical plane gives a likeness, and you will have all the [relative] heights and prominences of the figure. And the breadth or thickness which are on the upright wall m n are to be drawn in their proper form, since, as the wall recedes the figure will be foreshortened by itself; but [that part of] the figure which goes into the cove you must foreshorten, as if it were standing upright; this diminution you must set out on a flat floor and there must stand the figure which is to be transferred from the vertical plane r n 251 in its real size and reduce it once more on a vertical plane; and this will be a good method 252 .
263:251 17: che leverai dalla pariete r n. The letters refer to the larger sketch, No. 3 on Pl. XXXI.
263:252 18: Leonardo here says nothing as to how the image foreshortened by perspective and thus produced on the vertical plane is to be transferred to the wall; but from what is said in Nos. 525 and 523 we may conclude that he was familiar with the process of casting the enlarged shadow of a squaring net on the surface of a wall to guide him in drawing the figure.
Pariete di rilieuo; "sur une parai en relief" (RAVAISSON). "Auf einer Schnittlinie zum Aufrichten" (LUDWIG). The explanation of this puzzling expression must be sought in No. 545, lines 15-17.
263:253 : See Pl. XXXI. 3. The second sketch, which in the plate is incomplete, is here reproduced and completed from the original to illustrate the text. In the original the larger diagram is placed between lines 5 and 6.
1. 2. C. A. 157a; 463a has the similar heading: 'del cressciere della figura', and the text begins: "Se voli fare 1a figura grande b c" but here it breaks off. The translation here given renders the meaning of the passage as I think it must be understood. The MS. is perfectly legible and the construction of the sentence is simple and clear; difficulties can only arise from the very fullness of the meaning, particularly towards the end of the passage.