La Femme hydropique

In a Dutch physician's world of the 1660s, before anyone understood infection or the circulation of the blood, a doctor read your illness in a glass. Here one holds a flask of the patient's urine up to the window and studies its colour against the light, the standard bedside diagnosis of the age. The swollen woman sinking into her chair has dropsy, the old name for the fluid that gathers when the heart or kidneys fail, and her daughter kneels weeping at her side. Gerrit Dou trained briefly under Rembrandt in Leiden, then spent his life on this kind of jewel-like precision, working so small he ground his own fine brushes. It became one of the first paintings given to the new Louvre, in 1799.