He supported himself by grinding lenses, which was no lowly menial occupation, as it is often presented to have been in romanticizing versions of the philosopher's life, but was rather a craft that drew extensively from Spinoza's serious interest in the science of optics. The quality of his wares was highly valued by other scientists of his day. The important Dutch astronomer Christiaan Huygens, who discovered Saturn's rings as well as one of its four moons, preferred Spinoza's lenses to all others. "The [lenses] that the Jew of Voorburg has in his microscopes have an admirable polish," Huygens wrote to his brother in 1667. The one part of the romantic lens-grinding legend that is sadly true is that the dust from the optical polishing was unhealthy for Spinoza, whose mother and brother had both died young from tuberculosis. He himself succumbed to the disease at the age of forty-four.