Saint Thomas On The Good Shepherd

From His Commentary on the Holy Gospel According to Saint John:

Here he mentions four actions of a good shepherd: the first being that he knows his sheep. He says, he calls his own sheep by name, which shows his knowledge of and familiarity with his sheep, for we call by name those whom we know familiarly: "I know you by name" (Ex 33:17). This is part of the office of a shepherd according to: "Be diligent to know the countenance of your flock" [Prv 27:23]. This applies to Christ according to his present knowledge, but even more so considering eternal predestination, by which he knew them by name from eternity: "He determined the number of the stars, he gives to all of them their names" (Ps 147:4); "The Lord knows those who are his" (2 Tim 2:19).

The second action of a good shepherd is that he leads them out, i.e., he separates them from the society of those who are evil: "He brought them out of darkness and gloom" (Ps 107:14).

The third is that having separated them from evil and having brought them into the sheepfold, he has brought out all his own, from the sheepfold. He does this, first, for the salvation of others: "I will send survivors to the nations" (Is 66:19); "Behold, I send you as sheep in the midst of wolves" (Matt 10:16), so that they can make sheep out of the wolves. Secondly, they are to show the direction and way to eternal life: "To guide our feet into the way of peace" (Lk 1:79).

Fourthly, the good shepherd goes before his sleep by the example of a good life; so he says, he goes before them, although this is not what the literal shepherd does, for he follows, as in "I took him from following the ewes" [Ps 78:70]. But the good shepherd goes before them by example, "not as domineering over those in your charge but being examples to the flock" (1 Pet 5:3). And Christ does go before them: for he was the first to die for the teaching of the truth - "If any man would come after me, let him deny himself and take up his cross and follow me" (Matt 16:24); and he went before all into everlasting life - "He who opens the breach will go up before them" (Mic 2:13).