BUT how art thou compassionate, and, at the same time, passionless? For, if thou art passionless, thou dost not feel sympathy; and if thou dost not feel sympathy, thy heart is not wretched from sympathy for the wretched; but this it is to be compassionate. But if thou art not compassionate, whence cometh so great consolation to the wretched? How, then, art thou compassionate and not compassionate, O Lord, unless because thou art compassionate in terms of our experience, and not compassionate in terms of thy being.
Truly, thou art so in terms of our experience, but thou art not so in terms of thine own. For, when thou beholdest us in our wretchedness, we experience the effect of compassion, but thou dost not experience the feeling. Therefore, thou art both compassionate, because thou dost save the wretched, and spare those who sin against thee; and not compassionate, because thou art affected by no sympathy for wretchedness.
Taken from Proslogium (CHAPTER VIII).