From: The Dialogue of St. Catherine of Siena, translated by Algar Thorold, pgs. 194-195
She [the soul] further knows that she can be of no use to Me and can in no way repay Me that pure love with which she feels herself to be loved by Me, and therefore endeavours to repay it through the medium which I have given her, namely, her neighbour, who is the medium through which you can all serve Me. For, as I have said to thee, you can perform all virtues by means of your neighbour, I having given you all creatures, in general and in particular, according to the diverse graces each has received from Me, to be ministered unto by you; you should therefore love them with the same pure love with which I have loved you. That pure love cannot be returned directly to Me, because I have loved you without being Myself loved, and without any consideration of Myself whatsoever, for I loved you without being loved by you – before you existed; it was, indeed, love that moved Me to create you to My own image and similitude. This love you cannot repay to Me, but you can pay it to My rational creature, loving your neighbour without being loved by him and without consideration of your own advantage, whether spiritual or temporal, but loving him solely for the praise and glory of My Name, because he has been loved by Me.