The following is taken from the Dialogue of St. Catherine of Sienna. In this passage, Christ speaks to her of imperfect love of Him and of neighbor.
How an imperfect lover of God loves his neighbor also imperfectly, and of the signs of this imperfect love.
"And I would have you know that just as every imperfection and perfection is acquired from Me, so is it manifested by means of the neighbor. And simple souls, who often love creatures with spiritual love, know this well, for, if they have received My love sincerely without any self-regarding considerations, they satisfy the thirst of their love for their neighbor equally sincerely.
"If a man carry away the vessel which he has filled at the fountain and then drink of it, the vessel becomes empty, but if he keep his vessel standing in the fountain, while he drinks, it always remains full. So the love of the neighbor, whether spiritual or temporal, should be drunk in Me, without any self-regarding considerations.
"I require that you should love Me with the same love with which I love you. This indeed you cannot do, because I loved you without being loved. All the love which you have for Me you owe to Me, so that it is not of grace that you love Me, but because you ought to do so. While I love you of grace, and not because I owe you My love.
"Therefore to Me, in person, you cannot repay the love which I require of you, and I have placed you in the midst of your fellows, that you may do to them that which you cannot do to Me, that is to say, that you may love your neighbor of free grace, without expecting any return from him, and what you do to him, I count as done to Me, which My Truth showed forth when He said to Paul, My persecutor -- 'Saul, Saul, why persecute you Me?' This He said, judging that Paul persecuted Him in His faithful.
"This love must be sincere, because it is with the same love with which you love Me, that you must love your neighbor. Do you know how the imperfection of spiritual love for the creature is shown? It is shown when the lover feels pain if it appear to him that the object of his love does not satisfy or return his love, or when he sees the beloved one's conversation turned aside from him, or himself deprived of consolation, or another loved more than he.
"In these and in many other ways can it be seen that his neighborly love is still imperfect, and that, though his love was originally drawn from Me, the Fountain of all love, he took the vessel out of the water, in order to drink from it. It is because his love for Me is still imperfect, that his neighborly love is so weak, and because the root of self-love has not been properly dug out. Wherefore I often permit such a love to exist, so that the soul may in this way come to the knowledge of her own imperfection, and for the same reason do I withdraw myself from the soul by sentiment, that she may be thus led to enclose herself in the house of self-knowledge, where is acquired every perfection. After which I return into her with more light and with more knowledge of My Truth, in proportion to the degree in which she refers to grace the power of slaying her own will.
"And she never ceases to cultivate the vine of her soul, and to root out the thorns of evil thoughts, replacing them with the stones of virtues, cemented together in the Blood of Christ crucified, which she has found on her journey across the Bridge of Christ, My only-begotten Son. For I told you, if you remember, that upon the Bridge, that is, upon the doctrine of My Truth, were built up the stones, based upon the virtue of His Blood, for it is in virtue of this Blood that the virtues give life."