stotle, and his follower
Themistius, Siresius the Platonic; who so far relied on dreams which
some accident or other brought about, that they thence endeavoured to
persuade men there are no dreams but what are founded on realities. For,
say they, as the celestial influences produce various forms and changes
in corporeal matter, so out of certain influences, predominating over
the power of the fancy, the impression of visions is made, being
consentaneous, through the disposition of the heavens, to the effect
produced; more especially in dreams, because the mind, being then at
liberty from all corporeal cares and exercises, more freely receives the
divine influences: it happens, therefore that many things are revealed
to them that are asleep, which are concealed from them that are awake.
With these and such reasons it is pretended that much is communicated
through the medium of dreams:

When soft sleep the body lays at ease,
And from the heavy mass the fancy frees,
Whate'er it is in which we take delight,
And think of most by day we dream at night.

The transition from sleep is very natural to that of dreams, the
wonderful and mysterious phenomena of that state, the ideal transactions
and vain illusions of the mind. According to Wolfius, an eminent
philosopher of Silesia, every dream originates in some sensation, and is
continued by the succession of phantoms; but no phantasm can arise in
the mind without some previous sensation. And yet it is not easy to
confirm this by experience, it being often difficult to distinguish
those slight sensations, which give rise to dreams, from phantasms, or
objects of imagination.[81] The series of phantasms which thus constitute
a dream, seems to be accounted for by the law of the imagination, or
association of ideas; though it may be very difficult to assign the
cause of every minute difference, not only in different subjects, but in
the same, at different times, and in different circumstances. And hence
M. Formey, who adopts the opinion of Wolfius, concludes, that those
dreams are supernatural, which either do not begin by sensation, or are
not continued by the law of imagination.[82]

The opinion is as old as Aristotle, who asserted, that a dream is only
the [Greek: Phantasma] or _appearance_ of things, excited in the mind,
and remaining after the objects are removed.[83] The opinion of
Lucretius, translated in our motto, was likewise that of Tully.[84] Locke
also tra