Lydia Petrovna Andreyeva was the only sister of the academician Ivan Petrovich Pavlov. She was 25 years younger than him. Her room in the Pavlov house in Ryazan was quite different from the rooms of her brothers, who were fond of chemistry experiments, taxidermy, and collecting butterflies. In Lydia’s room, there is a small copper box on the dressing table. Its shape resembles that of a chest with a convex lid. The box cannot be closed with a key, as there is no lock — only an imitation.

Inside, the box is divided into three compartments with vertical partitions and a sloping bottom. The box is very small and can easily fit the palm. It could be used for storing rings, earrings and pendants, but only a few pieces at a time. In truth, a chest from the collection of the Ivan Pavlov Museum Estate is not a jewelry box — it was intended for storing postage stamps that were pasted on envelopes or postcards. Hence the name of the chest — the stamp box.

Inside stamp boxes, there could be up to five compartments, each holding a stamp of a certain value. Correspondence was the most popular method of communication in the 19th century: letters were sent every day, and it was convenient to keep stamps at hand on the table. Ivan Pavlov and Lydia Andreyeva lived in different cities, so they wrote letters to each other regularly.

In one of the letters to his sister, Ivan Pavlov wrote,