"It is said (Malachi 1:2-3): 'I have loved Jacob, but have hated Esau. I answer that, God does reprobate some. For it was said above A. 1) that predestination is part of providence. To providence, however, it belongs to permit certain defects in those things which are subject to providence, as was said above (Q. 22, A. 2). Thus, as men are ordained to eternal life through the providence of God, it likewise is part of that providence to permit some to fall away from that end; this is called reprobation. Thus, as predestination is part of providence in regard to those ordained to eternal salvation (cf. Q. 23, A. 4), so reprobation is a part of providence in regard to those who turn aside from that end. Hence reprobation implies not only foreknowledge, but also something more, as does providence, as was said above (Q. 22, A. 1). Therefore, as predestination includes the will to confer grace and glory; so also reprobation includes the will to permit a person to fall into sin, and to impose the punishment of damnation on account of that sin."
- St. Thomas Aquinas, Summa Theologica Part I, Question 23, Article 3 (New York, NY: Benzinger Bros., 1948).