For there are some eunuchs, which were so born from their mother's womb: and there are some eunuchs, which were made eunuchs of men: and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven's sake. He that is able to receive it, let him receive it. Eunuchs - Ευνουχος, from ευνην εχειν, to have the care of the bed or bedchamber; this being the principal employment of eunuchs in the eastern countries, particularly in the apartments of queens and princesses. These are they whom our Lord says are made eunuchs by men, merely for the above purpose.
So born from their mother's womb - Such as are naturally incapable of marriage, and consequently should not contract any.
For the kingdom of heaven's sake - I believe our Lord here alludes to the case of the Essenes, one of the most holy and pure sects among the Jews. These abstained from all commerce with women, hoping thereby to acquire a greater degree of purity, and be better fitted for the kingdom of God: children they had none of their own, but constantly adopted those of poor people, and brought them up in their own way. Philo, Josephus, and Pliny have largely described this very singular sect; and Dean Prideaux, with his usual fidelity and perspicuity, has given the substance of what each has said. Connex. vol. iii. p. 483, etc.; edit. 1725. The account is very interesting, and well worthy the attention of every Christian. Among the rabbins we find these different kinds of eunuchs, not only mentioned, but circumstantially described, סריס חמה saris chama, eunuchs of the sun, i.e. eunuchs by the hand of God; men born impotent. סריס אדם saris Adam, eunuchs of men, those who were castrated. And they add a third sort; those who make themselves eunuchs, abstain from marriage, etc., that they may give themselves Up to the study of the Divine law. See many examples in Schoettgen.
He that is able to receive - Χωρειν χωρειτω. These words are variously translated: he who can take; let him take it; comprehend, let him comprehend it: admit, let him admit it. The meaning seems to be, Let the man who feels himself capable of embracing this way of life, embrace it; but none can do it but he to whom it is given, who has it as a gift from his mother's womb.
The great Origen, understanding the latter clause of this verse (which I have applied to the Essenes) literally - O human weakness! - went, and literally fulfilled it on himself!