Descartes's letters indicate that he began work on the Meditations in
November 1639. By then he had been living in Holland for about ten
years, never for very long at the same address. Accounts of this period
of his life sometimes picture him as a near recluse, living with a few
servants away from society, wholly occupied with experimental and
theoretical work in the sciences, occasionally dabbling in philosophy.
His isolation has usually been exaggerated, however. Descartes had a
number of close friends, among them a famous co-worker in optical
theory, Constantin Huyghens, a professor of mathematics at the
University of Leyden called Franz Schooten, and, before they fell out,
Beeckman. With these and other people he exchanged regular visits
and letters, depending where he made his home.

The little that is known about Descartes's purely private life mostly
concerns his days in Holland. Perhaps in Deventer, where a young
follower of his got an academic post in 1632, Descartes met a woman
called Helène, who became his lover and the mother of his illegitimate
daughter. The daughter was baptized Francine on 7 August 1635. After
1635 Francine and Helène seem to have lived apart from Descartes and
to have visited him at irregular intervals. He tried to conceal from
outsiders their relationship to him, pretending when they came to visit
that Francine was his niece. When the little girl was five, in September
1640, she was taken ill with a fever and died. Descartes called it the
greatest sorrow of his life.

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