e favour he enjoyed, that, some years afterwards, Elizabeth condescended
to pay him a visit at his house in Mortlake, to view his museum of
curiosities, and when he was ill, sent her own physician to attend upon
him.

Astrology was the means whereby he lived, and he continued to practise it
with great assiduity; but his heart was in alchymy. The philosopher's
stone and the elixir of life haunted his daily thoughts and his nightly
dreams. The Talmudic mysteries, which he had also deeply studied,
impressed him with the belief, that he might hold converse with spirits
and angels, and learn from them all the mysteries of the universe. Holding
the same idea as the then obscure sect of the Rosicrucians, some of whom
he had perhaps encountered in his travels in Germany, he imagined that, by
means of the philosopher's stone, he could summon these kindly spirits at
his will. By dint of continually brooding upon the subject, his
imagination became so diseased, that he at last persuaded himself that an
angel appeared to him, and promised to be his friend and companion as long
as he lived. He relates that, one day, in November 1582, while he was
engaged in fervent prayer, the window of his museum looking towards the
west suddenly glowed with a dazzling light, in the midst of which, in all
his glory, stood the great angel Uriel. Awe and wonder rendered him
speechless; but the angel smiling graciously upon him, gave him a crystal,
of a convex form, and told him that whenever he wished to hold converse
with the beings of another sphere, he had only to gaze intently upon it,
and they would appear in the crystal, and unveil to him all the secrets of
futurity.[41] Thus saying, the angel disappeared. Dee found from
experience of the crystal that it was necessary that all the faculties of
the soul should be concentrated upon it, otherwise the spirits did not
appear. He also found that he could never recollect the conversations he
had with the angels. He therefore determined to communicate the secret to
another person, who might converse with the spirit while he (Dee) sat in
another part of the room, and took down in writing the revelations which
they made.

[41] The "crystal" alluded to appears to have been a black stone,
or piece of polished coal. The following account of it is
given, in the supplement to Granger's _Biographical History_.
"The black stone into which Dee used to call his
spirits was