Augustine of Hippo

Christ rose again from the seed of David, as the son of David, because he had emptied himself. How did he empty himself? By taking what he was not, not by losing what he was. He emptied himself; he humbled himself. Though he was God, he made himself known as a man. He was despised as he walked the earth, though he made the sky. He was despised as a mere man, as though he had no power. Not only despised, but on top of that also killed. He was a stone lying flat; the Jews stumbled over him and were shaken. …

Sermon 92:2 ↗

Thomas Aquinas

287. And he shall be. Here he sets out the fruit of obedience: sanctification to you, I will make you holy: I am the Lord who sanctify you (Lev 22:9). For a stone, he sets out the punishment of impeding rebels under the metaphor of travelers; and first, he sets out the occasion, second, the reception of the punishment: and very many of them shall stumble (Isa 8:15). And he sets out the occasion first, as to the people; second, as to the princes: for a snare. …

Commentary on Isaiah ↗