In the Orthodox Christian world an icon is not merely a picture but a "window" opening onto the holy; the icon painter therefore follows not personal invention but the sacred forms of tradition. Within this tradition, passed from Byzantium to Russia, the monk Andrei Rublev (c. 1360–1430) left the rare trace of an individual genius.

His "Trinity" icon, made around 1411 (by some accounts 1425–27), takes as its subject the scene of God appearing to Abraham as three strangers (angels); but Rublev reduces the narrative to a minimum. What remains is three angels, a table, and a cup upon it. The three figures are nearly identical; their heads slightly bowed, a silent conversation, a love, circulating among them. The composition settles into a circle — a closed, tranquil unity with no beginning and no end.

Rublev's innovation is in colour and feeling. In place of the dark, heavy, stern expression of the Byzantine icon, he sets bright golden tones, a soft blue (the famous, now-faded "Rublev blue"), and elegant, elongated figures. Instead of a rigid theological statement he offers a meditation on stillness and harmony. In the faces there is neither threat nor judgement but calm.

The icon became a national symbol of Russian art; Rublev was canonised a saint by the Orthodox Church centuries later. In a period when Western art history so often revolves around the Renaissance, Rublev's Trinity shows how high a wholly different visual language — an art seeking not space but spirit, not volume but stillness — could rise, in the very century that the revolution of perspective was born in Florence.