(In this double capacity, these auratic numbers also institute the formal composition of the Last Supper. [23]) With the addition of the female genitalia, supplemented by three views, the initial 12 becomes 15 – an opaque number devoid of a semiotic field. The female organs, Leonardo notes here, have «great mystery because of the uterus and its fetus» (gran misterio, mediante la matrice et suo feto). The number 15 seems to me to retain the excess of the «great mystery» that lies beyond the transparent order of the male body. This addition would therefore tacitly hint at the over-rigidity and inappropriateness of the purportedly «full knowledge» implied in the number 12, without, however, disrupting it yet. Disruption will happen when Leonardo will turn to the hand on this page.

Having done with the central column that designates the rationale and practice of the ‹cosmographic›-anatomical project, Leonardo turns to the vacant space on the right margin and opens a digression entitled «On the hand from within» (Della mano di dentro). This textual addendum describes in detail the demonstrations required for the investigation of the hand. It is obvious that Leonardo tries here to keep track with his initial vision, but he gets more and more confused and confusing along the way. He starts with a description of the necessary presentations of the bones of the hand: first the general view «from within», then views of the bones «sawn through the middle» and cut longitudinally. He then numbers ten demonstrations in the reverse order of the dissection. The first is to be the osteological core, and the last being «The whole hand complete and finished with its skin, and its measurements (la mano intera e finita colla sua pelle con le sua misure), and the same for the measurements of the bones».

It is evident that the said list does not correspond to the scholastic quadruple system that Leonardo earlier posited for the «cosmography of the lesser world». When it comes to the hand, the plan accumulates specific studies of the tendons and muscles that enable specific movements of specific fingers, and tellingly, also the intact, pre-dissected hand with its «measurements». (This last phase, the first in the actual order of the work, retains the life of the dead organ and absolves the malaise of dissection by the ritual of art. Leonardo’s extant anatomical studies of the hand do not include it however). Following that, Leonardo instructs the investigator thus: «what you do from this side of the hand do also from the other three aspects, that is from the inner side (parte dimestica), from the dorsal side (parte dorsale), from the back-external side (parte silvestra), and from the aforesaid side. [24] And thus in the chapter on the hand you will make 40 demonstrations.» These, apparently, do not include the several horizontal and longitudinal cuts of bones, nor the final studies of the proportions of each finger. But is this the end? It is unclear.