use the beauties of earth as steps along which he mounts upwards
for the sake of that other beauty, going from one to two, and from
two to all fair forms, and from fair forms to fair practices, and
from fair practices to fair notions, until from fair notions he
arrives at the notion of absolute beauty, and at last knows what
the essence of beauty is. This ... is that life above all others
which man should live, in the contemplation of beauty absolute.[4]

That is a passage whose music re-echoes through many pages of English
literature, especially in the poems of Spenser, Shelley, and Keats.

Plato may therefore be regarded as the source of speculative mysticism
in Europe, but it is Plotinus, his disciple, the Neo-platonist, who is
the father of European mysticism in its full sense, practical as well as
speculative, and who is also its most profound exponent. Plotinus (A.D.
204-270), who was an Egyptian by birth, lived and studied under Ammonius
Sakkas in Alexandria at a time when it was the centre of the
intellectual world, seething with speculation and schools, teachers and
philosophies of all kinds, Platonic and Oriental, Egyptian and
Christian. Later, from the age of forty, he taught in Rome, where he was
surrounded by many eager adherents. He drew the form of his thought both
from Plato and from Hermetic philosophy (his conception of Emanation),
but its real inspiration was his own experience, for his biographer
Porphyry has recorded that during the six years he lived with Plotinus
the latter attained four times to ecstatic union with "the One."
Plotinus combined, in unusual measure, the intellect of the
metaphysician with the temperament of the great psychic, so that he was
able to analyse with the most precise dialectic, experiences which in
most cases paralyse the tongue and blind the discursive reason. His
sixth Ennead, "On the Good or the One," is one of the great philosophic