This page analyzes another hidden image by Leonardo da Vinci, created through optical-illusion techniques. The figure is commonly referred to as “the devil” and is explicitly echoed in a passage of the Treatise on Painting.
The image is concealed mainly through a technique of tonal variation, and partly through an intentional organization of the background form. The foreground figure has a relatively uniform base color, while the hidden face emerges from minimal tonal differences within the lamb’s form.
These slight chromatic variations prevent immediate recognition, yet they are sufficient to build a coherent figure when observed carefully. A simple tonal-threshold reading makes the details legible: a vaguely human and monstrous figure, with hairy ears resembling horns.
What, in the primary iconographic reading, corresponds to the lamb’s foreleg can be read, in the secondary reading, as a “thigh” that the monstrous figure appears to devour. Given the unsettling nature of this transformation — the lamb is the Child’s play companion in the painting — and the morphological features of the face, the image has been identified as “the devil”.
A textual resonance for this interpretation appears in the Treatise on Painting, where Leonardo notes that, in stains and confused forms, one may recognize “monstrous things, such as devils and similar things”. The plural suggests that such images are not an isolated case, but part of a broader practice of figurative invention.
To observe this image correctly, it is necessary to rotate the painting 90° counterclockwise (see the dedicated page How to observe the hidden images). The main portion of the face lies within the lamb’s area between the Child’s right leg and left foot; in this configuration, the lamb’s leg can be read as detached from the body and incorporated into the monstrous figure.
The base image reproduces the detail as it appears in the Musée du Louvre’s photographic documentation.
In the original painting the area is more readable than in the digital photograph,
which tends to compress tonal variations in the darkest passages.
Hover with the mouse (or press and hold on touch screens) to view a support overlay,
obtained through a global rebalance of tonal values and the application of a selective mask.
The white areas indicate only the portions that should not be considered in the reading,
and they do not constitute outlines or added graphic elements.
In sfumato painting, edges are never rigidly defined:
the figure is constructed through light, shadow, and volumetric continuity.
The overlay therefore has a purely analytical function.
The legibility of the figure does not depend only on the suggestion of a profile, but on the presence of coherent details that maintain volumetric and tonal relationships compatible with an intentional structure. Particularly significant are the figure’s left eye (visible on our right) and the teeth in relation to the lamb’s leg.
The detail highlights the figure’s left eye, visible on our right.
The orbital cavity, an upper shadow comparable to an eyelid,
and a lighter point corresponding to reflected light can be distinguished.
The eye’s orientation, consistent with the overall inclination of the face,
helps stabilize the volumetric reading.
In the lower portion of the face, the teeth are visible,
arranged in sequence along the oral margin.
In this configuration, the lamb’s leg becomes a “thigh”
that the monster is devouring.
The relationship between teeth, inner shadows, and surrounding masses
produces depth consistent with an open mouth integrated into the painting’s tonal continuity.
(On the left you can see the reproduction of the painting as it appears, without any alteration of the image. The oval only indicates the area where the figure is located. In this zone, Leonardo uses a tone slightly darker than the base color to build the essential lines and shadows that characterize the hidden face.)