In a letter to Hypatia of Alexandria, of whom he was a student, Synesius of Cyrene wrote that his essay, or as he called it “book” was:
“[…] set up as a thank-offering to the imaginative faculties. It contains an inquiry into the whole imaginative soul, and into some other points which have not yet been handled by any Greek philosopher. But why should one dilate on this? This work was completed, the whole of it, in a single night, or rather, at the end of a night, one which also brought the vision enjoining me to write it. There are two or three passages in the book in which it seemed to me that I was some other person, and that I was one listening to myself amongst others who were present.
Even now this work, as often as I go over it, produces a marvelous effect upon me, and a certain divine voice envelops me as in poetry. Whether this my experience is not unique, or may happen to another, on all this you will enlighten me, for after myself you will be the first of the Greeks to have access to the work.”
An extract from On Dreams:
“[…] divinations are amongst the best vocations of man; and if all things are signs appearing through all things, inasmuch as they are brothers in a single living creature, the cosmos, so also they are written in characters of every kind, just as those in a book some are Phoenician, some Egyptian, and others Assyrian.
The scholar reads these, and he is a scholar who learns by his natural bent. One reads some of them and another reads others, one reads more and another less. In the same way one reads them by syllables, another reads the complete phrase, another the whole story. In like manner do the learned see the future, some understanding stars, and of these, one the fixed stars, another those flames which shoot across the sky. Again, there are those who read it from the entrails, and from the cries of birds, and from their perches and flights. To others also what are termed omens are manifest, written indications these of things to be, and again voices and encounters otherwise intended, for all things have their significance for every one.  In the same way, if birds had had wisdom, they would have compiled an art of divining the future from men, just as we have from them; for we are to them, just as they are to us, alike young and old, very old and very fortunate. It must needs be, I think, the parts of this great whole, since it all shares one feeling and one breath, belong to each other. They are, in fact, limbs of one entire body, and may not the spells of the magicians be even such as these? Obviously, for charms are cast from one part of it to another, as signals are given, and he is a sage who understands the relationship of the parts of the universe. One thing he attracts to himself through the agency of another thing, for he has present with him pledges of things which are for the most part far away, to wit, voices, substances, figures. And as when the bowel is in pain, another part suffers also with it, so a pain in the finger settles in the groin, although there be many organs between these parts which feel nothing.
This is because they are both portions of one living organism, and there is that which binds them one to the other more than to other things. Even to some god, of those who dwell within the universe, a stone from hence and a herb is a befitting offering; for in sympathizing with these he is yielding to nature and is bewitched. Thus the harp-player who has sounded the highest note does not sound the sesquioctavus next, but rather strikes the epitrite and the nete, a heritage today from a more ancient state of harmony.
But there is in the cosmos, even as in human relationship, a certain discord also; for the universe is not one homogeneous thing but a unity formed of many. There are parts of it which agree and yet battle with other parts, and the struggle of these only contributes to a harmonious unity of the whole, just as the lyre is a system of responsive and harmonious notes. The unity resulting from the opposites is the harmony of both the lyre and the cosmos. Archimedes the Sicilian asked for a point of support outside of the earth wherefrom he might prop himself against the whole earth, for he said that as long as he was himself upon the earth he had no power over it. But the man, howso great his knowledge of the nature of the universe may be, once placed outside of it, could no longer make any use of his wisdom. He uses the universe against itself; accordingly his touch with it once lost, he will watch it in vain, and the lifeless symbols only would then be recorded. And small wonder, for whatever of the divine elements is outside the cosmos can in no wise be moved by sorcery.
He sits apart and careth not. nor taketh any thought thereof.
It is the nature of pure reason not to be deflected; it is only the emotional element which may be cajoled. Wherefore the multitude of things in the universe and their relationship furnish the bulk of the subject-matter in the initiations and prophecies. There is a multitude of the discordant elements, but a relationship is the unity of things existing. Now, as to initiations, let not our law-abiding discourse noise them abroad; there is no offense, however, in explaining divination.”
Letters of Synesius of Cyrene to Hypatia of Alexandria http://www.livius.org/su-sz/synesius/synesius_letter_154.html
Full text of Synesius On Dreams http://www.livius.org/su-sz/synesius/synesius_dreams_02.html