In our own wills we find both the passions (such as joy and love), and the habits of the moral virtues (such as justice and fortitude). Hence we considered the love (Q20) of God first, but now His justice and mercy (Q21) in four articles:
"It is because the contemporary alternatives seem so one-sided and are not more evidently solutions to the problems which Thomas faced, and partly solved, that we return to him and to the tradition of theology and philosophy in which his Summa Theologiae appears: theology as the science of the first principle and this as the total knowledge of reality in its unity." -- Wayne J. Hankey, God in Himself (Oxford University Press, 1987), p.159.