Animals show up in Leonardo's paintings and notebooks as symbols, pets, anatomical specimens and bestial lovers. In these roles, animals come under the dominion of human curiosity, communication, affection, or desire. But Leonardo's work also raises the possibility of non-human animals having experiences of the world, and therefore interior lives, of their own. While Leonardo sometimes compares animals unfavorably to humans, he often puts us linguistically on an even footing, speaking of humans and "other animals." For instance in the Codex Atlanticus, fol. 323r, he writes of omini vs. bestie, but in Manuscript G, fol. 44r, he speaks of omo and altro animale. Sense perception is one such context in which Leonardo looks at humans as just one variety of animals.
Leonardo's Portrait of Cecilia Gallerani (fig. 1) invites us to compare the perceptual experiences of a human and an animal. Both the woman and the ermine react to something, presumably the arrival of another person, but in distinct ways. Whereas art historian Martin Kemp saw "a gentle smile of welcome sparkling in [Gallerani's] eyes" (Kemp 1981, 201), the ermine looks wary, even hostile. Kenneth Clark commented that "no one but Leonardo could have conveyed its stoatish character, sleek, predatory, alert, yet with a kind of heraldic dignity" (Clark 1989, 98). The lower body of the ermine remains relaxed and supple on Gallerani's arm, but it supports its alert upper body on a limb whose muscles are tense and well articulated. The animal is a nexus of sensory experiences, some of which go beyond the human. Its gaze is intense. It is being caressed and restrained. Its half-moon ears are delicately rendered in contrast to Gallerani's, which are hidden by her hairdo. And its carefully delineated whiskers are drawn back, an apparently accurate observation by Leonardo of an attentive ermine (figs. 2 and 3).
Leonardo wrote frequently of the primacy of sensory experience: "All our knowledge has its origins in perceptions" (Codex Trivulzianus, fol. 20v; Richter, no. 6). Yet he is unequivocal in pointing out the poverty of human sense perception:
I have found in the composition of the human body that the organs of sense are duller and coarser as compared with those of the constitutions of animals. Thus it is composed of an instrument less ingenious and of parts less capable of receiving the power of the senses (Windsor, Royal Library 19030v; Richter, no. 158).
On a page of his notebooks where he compared and sketched the pupils of various animals, Leonardo concluded (fig. 4):
Man, however, having a more feeble sight than any other animal is less hurt by excessive light and his pupil undergoes less increase in dark places (Manuscript G, fol. 44r; Richter, no. 159).
Here is a dilemma that Leonardo acknowledged as artist, scientist and human animal: the great task of being human is comprehending nature through direct sensory experience, but human senses are poor. This dilemma raises some pressing questions.
1) An epistemological question: Are human senses adequate for scientific investigation, or will much of nature remain a mystery to us? Leonardo does not directly raise this doubt. Although he spent a great deal of time studying birds' wings so that humans might emulate flight, he does not suggest, for example, any optical devices that would allow us to emulate the keen sight of birds.
2) An artistic question: Can a painter allow us to imagine the heightened sense perception of other animals? I have not come across any writings in which Leonardo proposes this as one of the powers of painting. Nevertheless, his depiction of an ermine seems like a brilliant response to precisely this challenge. By directly addressing his viewers' limited human visual faculty, Leonardo lets us participate in the visual, auditory and olfactory experience of this non-human animal. Leonardo emphatically depicts an animal in the act of experiencing. Ermine typically have darkly pigmented eyes, but Leonardo has rendered them in a lighter hue that makes evident the pupils and hence the direction of an active gaze. The ermine's nose appears to be a working, sniffing organ. Martin Kemp rules out any possibility that Leonardo attempted to capture motion through visual blur. Still, I cannot help but see twitching in the layered outline of the animal's nose (fig. 2).
3) An ethical question: By acknowledging that other animals have sensory experiences that are both different from and superior to ours, is Leonardo nudging humans out of their traditionally central place in creation? It is undeniable that both the human form and the human intellect were central to Leonardo's work. (It would be hard to imagine Leonardo drawing a Vitruvian cat.) But Leonardo actually did imagine a cosmos that could carry on without humankind. In the Codex Arundel, Leonardo described a geological catastrophe in which "all the animals, finding no fresh grass for pasture, will perish" and "the human race will cease to be" (Codex Arundel, fol. 155v; Richter, no. 16). The presence of the ermine in Gallerani's portrait has been convincingly explained as a symbol for her, or her lover the ruler of Milan, or both. Yet Leonardo does not entirely subsume the ermine within a human code of significations. The animal's perceptual faculties declare that it exists apart from us.
In 1515, the Italian navigator Andrea Corsali wrote home from present-day India:
Certain infidels called Guzzarati do not feed upon anything that contains blood, nor do they permit among them any injury be done to any living thing, like our Leonardo da Vinci (Richter, no. 354).
Corsali's letter is further evidence that Leonardo was thinking about humans and other animals—linked pieces of the macrocosm of nature—in ways that were not only scientifically but also ethically innovative. To be sensitive to Leonardo's thought means to read without a preconception of where or whether there should be a human-animal divide.
Fig. 1 Portrait of Cecilia Gallerani (Lady with an Ermine), 1483-89, oil on wood, 55 x 40 cm, Czartoryski Museum, Cracow. (Scala / Art Resource, NY).
Fig. 2 Detail of Portrait of Cecilia Gallerani.
Fig. 3 An ermine, or "stoat" (Mustela erminea).
Fig. 4 Leonardo da Vinci, Pupil studies, Manuscript G, fol. 44r, Biblothéque de l'Institut de France, Paris.