Synesius of Cyrene (c.370-c.413) was a Neo-Platonic philosopher who became bishop of Ptolemais in the Cyrenaica. He left behind a small corpus of texts that offer much information about daily life in Late Antiquity, and about the christianization of the Roman world.
Synesius' On dreams consists of two parts:
- A philosophical explanation why dreams allow our soul to reach higher spheres, based on a doctrine that is derived from the philosophical school known as Stoa (sections1-7);
- A more down-to-earth, and very accessible, account of the way one must investigate one's dreams, which boils down to keeping a "night book"(section 8-13).
The text is offered here in the translation by A. Fitzgerald. The four-digit numbers are page numbers of the Migne edition.
Synesius, On dreams 11
 But it is high time that we should say of this art how it may help us. The best way is to prepare the divine pneuma in such wise that it may be worthy of the direction of mind and of God, and not be a recipient of obscure energies. And the best culture is the one leading through philosophy, which brings a calm from passions, for when once disturbed by these the pneuma is occupied, as it were a territory; and through a wise and temperate life, one that least maddens the animal nature and that has least tendency to bring it into the last body. For turmoil would reach even to the first body, but this ought to be kept unperturbed and unmoved. But since this is an easy prayer for every one to join in, but is of all things the most difficult to cooperate in attaining, then as we wish sleep to be unprofitable to none, come now, let us seek a definition even for indefinable things; in a word, let us put together an art of divining dream-images. Now it is something in this wise. When mariners sailing the sea come suddenly upon a rock, and presently disembarking see a city of men, as often as they see the same rock, they will take it as a sign of the city. And just as when, in the case of generals, we know from the scouts that they themselves will appear, though we do not see them (for that from the same indication they have always in the past appeared on the scene); so on each occasion we obtain from the dream imagines a signal of the activity of coming events.
 For these are forerunners of those same things, and like things are forerunners of like. Therefore it is the skipper's fault if, when the same rock becomes visible, he fails to recognize it, or is unstable to say what land the ship moving; and as such a man sails without a chart, in the same way the man who has often seen the same sight, if he fails to observe of what experience or fortune or event it is prophetic, such a man makes as foolish a use of his life as does the skipper in question of his ship. Thus we predict storms in a time of perfect atmospheric peace, the moment we see halos about the moon, because on many occasions when we have observed this appearance a tempest has followed.
When that a halo is single, then mayst thou foretell calm and windstorms;
Broken the hallo, then know that 'tis wind; when it fadeth, calm weather.
Once that the moon is surrounded by halos twain a storm cometh,
And should that ring grow to triple encirclement, storms rage the greater;
And even greater, if darkened; yet greater, if broken the halo.note[Aratus, Phaenomena 812-816.]
 Aristotle and reason assert that in every case sense-perception create memory, memory experience, experience to turn science. So let us treat the path to dreams. To this end many books have already been collected by certain men,note[E.g., the Book on dreams by Artemidorus of Daldis.] devoted to such observation. But for my part, I laugh at all these books and think them of little use.  For not like the last body, which is a combination of associated elements, can it [divination] accept a [system of] art and logic altogether comfortable to its nature, inasmuch as the body generally experiences the same results from the same causes, because the difference between bodies of like nature is small, and that amongst them which is contrary to nature is not diseased without our knowledge, nor do we adopt such a standard as this.
 This is not the case with the imaginative pneuma. In the first nature also things differ from another, because one thing belongs appropriately to one sphere, another to another, in proportion to the extent of the mingling.
Happy are they of a truth, nay happiest are they of all those
Souls whosoever are poured adown upon the earth from high heaven;
And they are happy, they also, although no renown be their portion,
So many as thyself, Oh Sovran, who shinest resplendent,
Spring into life e'en from Zeus and from might Necessity's spindle.note[Unknown.]
 Now this is what Timaeus set forth darkly, when he assigned to each soul its proper star; but those souls which left their proper nature, by loving to dwell in the region of matter, one of them more, another less, each of these, for as much as it has been unfortunate in its inclination, has sullied its pneuma, whose life is passed in error, and in a disease of the pneuma, a disease unnatural to the latter on account of its nobility, although natural to the animal being (for that itself was animated through a pneuma of this sort) unless it be that its nature is the grade in which it is enrolled of its own choice, through its practice of good and evil; for nothing is so versatile as the pneuma.
 How then in the case of things dissimilar by nature, law, and experience, could the same things be revealed by the same images? This is impossible; it could not be. How could troubled and limpid waters, stagnant and moving water be alike affected by the same shape? And if the difference of color, and the movements show themselves in various configurations, in this way alone would it be one in character, namely in always diverging from the clear-cut image. Now if such a difference exists, if accordingly some Phemonoe, or somebody's Melampus, or any individual you please, pretends to make some general definition and arrangement concerning such phenomena, let us ascertain from such men whether it is natural that the plane mirror, the distorted, and that made from dissimilar materials, should reflect a like image of the thing shown. Such men as these have not even done, I think, any philosophical thinking at all on the nature of the pneuma, although that which is proper to it, in whatsoever state it may be, they consider to be a rule and standard for everything. Now for my own part, I do not deny there is an element of likeness in dissimilar things; but I affirm that the obscure becomes all the more obscure by dispersion. The image of the thing which leaped out prematurely was, I presume, even in the beginning difficult to find out. It is even more difficult in an individual character to capture that which is like a general image.