John 10:14

Then because He said above "And the sheep hear his voice, and follow him," lest any should say, "What then is this to those who believe not?" hear what He addeth "And I know My sheep, and am known of Mine." As Paul declared when he said, "God hath not rejected His people whom He foreknew"; and Moses, "The Lord knew those that were His"; "those," He saith, "I mean, whom He foreknew." Then that thou mayest not deem the measure of knowledge to be equal, hear how He setteth the matter right by adding, "I know My sheep, and am known of Mine." But the knowledge is not equal. "Where is it equal?" In the case of the Father and Me, for there, "As the Father knoweth Me, even so know I the Father." Had He not wished to prove this, why should He have added that expression? Because He often ranked Himself among the many, therefore, lest any one should deem that He knew as a man knoweth, He added, "As the Father knoweth Me, even so know I the Father." "I know Him as exactly as He knoweth Me." Wherefore He said, "No man knoweth the Son save the Father, nor the Father save the Son", speaking of a distinct kind of knowledge, and such as no other can possess.

From both Christ distinguisheth Himself; from those who came to spoil, by saying, "I am come that they might have life, and that they might have more abundantly"; and from those who cared not for the sheep being carried away by wolves, by never deserting them, but even laying down His life for them, that the sheep might not perish. For when they desired to kill Him, He neither altered His teaching, nor betrayed those who believed on Him, but stood firm, and chose to die. Wherefore He continually said, "I am the good Shepherd." Then because His words appeared to be unsupported by testimony, (for though the, "I lay down My life," was not long after proved, yet the, "that they might have life, and that they might have more abundantly," was to come to pass after their departure hence in the life to come,) what doth He? He proveth one from the other; by giving His mortal life (He proveth) that He giveth life immortal. As Paul also saith, "If when we were enemies we were reconciled to God by the death of His Son, much more being reconciled we shall be saved." (Rom. v. 10.) And again in another place, "He that spared not His own Son, but delivered Him up for us all, how shall He not with Him also freely give us all things?" (Rom. viii. 32.)

When He saith, "As the Father knoweth me, even so know I the Father," who can be ignorant of His meaning? For He knoweth the Father by Himself, and we by Him. That He hath knowledge by Himself, we know already: that we also have knowledge by Him, we have likewise learned, for this also we have learned of Him. For He Himself hath said: "No one hath seen God at any time; but the only-begotten Son, who is in the bosom of the Father, He hath declared Him." And so by Him do we also get this knowledge, to whom He hath declared Him. In another place also He saith: "No one knoweth the Son, but the Father; neither knoweth any one the Father, save the Son, and he to whomsoever the Son will reveal Him." As He then knoweth the Father by Himself, and we know the Father by Him; so into the sheepfold He entereth by Himself, and we by Him.

(Hom. in Evang. xiv.) As if He said, I love My sheep, and they love and follow Me. For he who loves not the truth, is as yet very far from knowing it.

Hence the difference of the hireling and the Shepherd. The hireling does not know his sheep, because he sees them so little. The Shepherd knows His sheep, because He is so attractive to them.