Tears, usually pure water, with saline traces; but in cases of poisoning may show the poison, and in diabetes become saccharine like the other secretions. Serving normally to moisten eyeballs, interior eyelids, and nose, they are regularly secreted in normal quantities, and disappear by the duct into the nose. In man they are also the natural outlets of strong emotion, and are secreted in greatly increased quantity; they much more constantly accompany crises of fear, anxiety, grief, affection, and keen joy than physical pain. Old age is comparatively tearless.

Entry from Everybody's Cyclopedia, 1912.