here were other men who examined the various
substances of which the earth is composed, putting them together to
make new things. These were alchemists, and their great ambition was
to find some preparation which would change baser metals into gold.
This hoped-for preparation was spoken of as the "philosopher's stone."

Now modern learning has changed these vague experiments into exact
science; astronomy has replaced astrology, and chemistry has taken the
place of alchemy. Nevertheless these changes were brought about only
very gradually, and in the 17th century, when Rembrandt lived and
painted this picture, a great stir was made by the new ideas of
astronomy taught by Galileo in Italy, and the new discoveries in
chemistry made by Van Helmont in Belgium. Many philosophers still held
to the old beliefs of astrology and alchemy.

It is not likely that Rembrandt had any one philosopher in mind as the
subject of his picture. That his philosopher is something of a
scholar, we judge from the table at which he sits, littered with
writing materials. Yet he seems to care less for reading than for
thinking, as he sits with hands clasped in his lap and his head sunk
upon his breast. He wears a loose, flowing garment like a
dressing-gown, and his bald head is protected by a small skull cap.
His is an ideal place for a philosopher's musings. The walls are so
thick that they shut out all the confusing noise of the world. A
single window lets in light enough to read by through its many tiny
panes. It is a bare little room, to be sure, with its ungarnished
walls and stone-paved floor, but if a philosopher has the ordinary
needs of life supplied he wants no luxuries. He asks for nothing
more than quiet and uninterrupted leisure in which to pursue his
meditations.

[Illustration: THE PHILOSOPHER IN MEDITATION
_The Louvre, Paris_]

Our philosopher is well taken care of; for while his thoughts are on
higher things and eternal truths, an old woman is busy at the fire in
the corner. Evidently she looks after the material and temporal things
of life. She kneels on the hearth and hangs a kettle over the cheerful
blaze. The firelight glows on her face and gleams here and there on
the brasses hanging in the chimney-piece above. Here is promise of
something good to come, and when the philosopher is roused from his
musings there will be a hot supper ready for him.

There are two mysteries in the room which arouse our curiosity. In the
wall