In the center of the picture on a hot racer Jovanina Pacini is depicted. The horse is hot, but the rider sits straight and proud, self-confident. To the left of the young amazon-balcony, on which her younger sister ran, in the depths there is a shady park. The general silhouette of a horsewoman and a horse forms a semblance of a triangle – a stable, long-favorite form of building a ceremonial portrait.

So many compositions were decided by Titian, Velasquez, Rubens, Van Dyck. Under the Brullov brush, the old compositional scheme is interpreted in a new way. The artist enters the picture of the child in the picture. The little girl, hearing the horse’s tramp, rushed out onto the balcony and extended her hand through the bars. And delight, and fear for the rider expresses her face. The note of a living, immediate feeling moderates the cold majesty of the portrait, gives it spontaneity and humanity.

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I like that it's a huge piece of art, here it is in context: