For reference, the author is speaking of communion.
From the Rudder
CANON IV As for those men who involuntarily become victims of nocturnal emission, let them too be guided by their own conscience as to whether to indulge or not, and decide for themselves, whether they have any doubt about this matter or not, as also in the case of foods, “he that hath any doubt is damned if he eat” (Romans 14:23). And let everyone be conscientious in these matters, and out spoken, in accordance with his own inclination, when he approaches God. In honoring us (for you know you are, dear) by asking these questions, you have taken us to be like-minded, as indeed we are, and you are making us partners in your decision. As for me, it is not as a teacher, but as one who deems it fitting for us to talk with each other with all simplicity, that I have set forth my own conception of the matter for our common benefit. After finding that this conception of the matter.
Interpretation
In the present Canon the Saint is speaking about involuntary emission, or what is more commonly called a wet dream, which occurs during our sleep; and he says that all men who suffer this should make their own conscience the judge. For if the wet dream resulted without any obscene imagination and erotic thought, and furthermore without overeating and over-drinking, and instead nature alone did this of herself, as if it were a natural superfluity in the way of excrement, they are not prevented from coming to communion. But if it resulted from the causes above mentioned – that is to say, from imagination and erotic thought, or from excessive eating and excessive drinking, they ought to be forbidden communion, on the ground that they are not pure, not because of the emission itself of the semen (since this is not unclean, seeing that it is a natural product, precisely as neither the flesh is unclean in itself, of which the semen is an excretion), but because of the wicked contemplation and imagination which polluted the mind. Such men as these, then, are not conscientious, and accordingly they are not outspoken, owing to the wicked contemplation and imagination they give rein to. Hence, both as doubters and as being convicted or reproved by their conscience,
How can they approach God and the Mysteries? For if they approach while thus doubting, they are rather condemned, and not sanctified, just like one who is condemned for eating the common and unclean animals forbidden to Jews, if he doubts and hesitates about these, as the Apostle says.
Canon XII of Timothy is in effect a more detailed explanation of the present Canon. For it interprets this reproof of the conscience of one who has had a wet dream. Accordingly, if he is reproved and convicted of having had this happen to him as the result of a desire for a woman-or, in other words, an erotic thought and imagination-he must not partake; but if it was the result of the influence of demons that this happened to him, he may commune. Since, however, it is difficult for one to discern when the cause of his wet dream is traceable to the enviousness and influence of demons, without his providing any occasion for it himself, the safest way is not to commune. For a wet dream may result from either overeating or over-drinking or oversleeping, and from negligence and repose, and from languor of the body, and from pride, and condemnation, and aspersion, and from some illness of the body, and from a wicked habituation to fornication, and from toil and the drinking of cold beverages. Oftentimes it is due to fear of having a wet dream, according to Symeon the modern Theologian (and see the reply No. S of Anastasios the Sinaite, and Philokalia on page 908). For this reason too the Faster in his c. VI forbids one who has polluted himself in sleep from communing for one day. John of Citrus and Balsamon in Reply No. 1 likewise excludes priests and laymen for a day if they have had a wet dream, with the sole exception that in case of danger a layman may partake of the Body and Blood of the Lord, or a priest may celebrate Divine Liturgy, even though he has had a wet dream. So say also Symeon of Thessalonica in his replies No. 14 and 15, and the Lausaicum in the discourse concerning Dioscoros, and Barsanuphios the great one among Fathers.