Synesius, Dreams 12
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 12
 For this reason we must dismiss the idea that all men are under the same laws;  rather must each man hold himself as material for the art. Let him inscribe on his memory the affairs in which he has been involved, and the nature of the visions which have preceded them.
 Mastery in the art is acquired without difficulty where necessity is involved in the practice. The need reminds one of the practice, and especially on every occasion that it is well off for material. For what could be more abundant than dreams, and what more fascinating? These induce even fools to pay heed to them. It would therefore be shameful for those who have lived ten years beyond adolescence to stand in need of any other diviner, shameful that they should not have accumulated an abundant store of technical principles.
 It should be a wise proceeding even to publish our waking and sleeping visions and their attendant circumstances; the things to do, I say, unless the culture of the city is like to be too rustic for so novel an enterprise. We shall therefore see fit to add to what are called "day books" what we term "night books", so as to have records to remind us of the character of each of the two lives concerned; for our argument already laid it down that certain life exists in imagination, at one moment better, at another worse than the intermediate, according to the relation of the pneuma to health and disease. If in this way, therefore, we make profitable the observation by which the art is developed, and if nothing slips our memory, in other respects also the result will be a refined pastime; it will be paying oneself the compliment of a history of one's waking and sleeping moments.
 And to those who occupy themselves with public speaking, I do not know any other foundation to replace this as a comprehensive basis for exercise in the power of speech; for if the sophist of Lemnos says that the day books are good teachers of effective oratory on every subject, for that they do not overlook matters of lesser importance, but compel one to go through the trivial and the serious alike, is it not worth while to value night books as a subject for oratory?
 Any one can see how great the work is, on attempting to fit language to visions, visions of which those things which are united in nature are separated, and things separated in nature are united, and he is obliged to show in speech what has not been revealed. It is no mean achievement to pass on to another something of a strange nature that has stirred in one's own soul, for whenever by this fantasy [of dreaming] things which are expelled form the order of being, and things which never in any possible way existed, are brought into being - nay, even things which have not a nature capable of existence, what contrivance is there for presenting a nameless nature to things which are per se inconceivable? Again, it [the fantasy] neither makes these forms appear numerous and all present at the same moment, nor yet does it present them after an interval, but exactly as the dream itself might have them and pass them on to us; for we believe whatever it wills us to believe. To survive at all and without cutting a sorry figure amidst all this, would be proof of a masterly rhetoric. It conducts itself wantonly even against our understanding itself, becoming the cause of something more than thought. For we are not indeed insensible to the visions; rather our approbations and partialities strong, and not least our detestations. And the many trickeries that are bound up with this, attack us in our sleep. Pleasure is at that moment most of all a thing full of charm, such as to impart to our souls loves or hatreds even in the waking state. If any one were to utter no lifeless words, but rather to accomplish that for the sake of which the discourse was seriously undertaken, he would need stirring language to put his auditor into the same condition  and amidst the same thoughts as himself.
 Now in dreams one conquers, walks, or flies simultaneously, and the imagination has room for it all; but how shall mere speech find room for it? So a man sleeps and dreams; he sees a dream, and arises from it still sleeping, as he thinks, and shakes off his dream while still recumbent. He philosophizes a little on the vision that has appeared to him, according to his knowledge; and this is a dream, but the other is a double dream. Accordingly he believes it not, and thinks now he is awake and that what appears to him is really alive. Forthwith a fierce struggle ensues, and a man dreams that an attack is made on himself, then he has left all behind and he is waking up, again that he has made trial of himself and has discovered the deception.
 In such a way must the sons of Aloeus be suffering the punishment for piling up the mountains of Thessaly against the gods. But there is no law of Adrastea [Justice] in the way of the sleeper, to forbid him from rising from earth more happily than Icarus, from soaring above the eagles, or reaching a point above the loftiest spheres themselves. So one looks steadily upon the earth from afar, and discovers a land not visible even to the moon. It is also in his power to hold converse with the stars and to meet the unseen gods of the universe. That which is difficult to describe takes place easily, namely that the gods are visibly manifest, nor do the gods even feel even a particle of jealousy. The dreamer has not even descended to the earth after a short interval; he is already there. Nothing is so characteristic of dreams as to steal space and to create without time. The sleeper then converses with sheep and fancies their bleating to be speech, and he understand their talk. So new and so extensive a wealth of subjects is there for one who has the courage to let loose his language upon them.