I answer that, As stated above (A. 1, ad 3), a twofold joy in God arises from charity. One, the more excellent, is proper to charity; and with this joy we rejoice in the Divine good considered in itself. This joy of charity is incompatible with an admixture of sorrow, even as the good which is its object is incompatible with any admixture of evil: hence the Apostle says (Phil. 4:4): "Rejoice in the Lord always."
The other is the joy of charity whereby we rejoice in the Divine good as participated by us. This participation can be hindered by anything contrary to it, wherefore, in this respect, the joy of charity is compatible with an admixture of sorrow, in so far as a man grieves for that which hinders the participation of the Divine good, either in us or in our neighbor, whom we love as ourselves.
Reply Obj. 1: Our neighbor does not weep save on account of some evil. Now every evil implies lack of participation in the sovereign good: hence charity makes us weep with our neighbor in so far as he is hindered from participating in the Divine good.
Reply Obj. 2: Our sins divide between us and God, according to Isa. 59:2; wherefore this is the reason why we grieve for our past sins, or for those of others, in so far as they hinder us from participating in the Divine good.
Reply Obj. 3: Although in this unhappy abode we participate, after a fashion, in the Divine good, by knowledge and love, yet the unhappiness of this life is an obstacle to a perfect participation in the Divine good: hence this very sorrow, whereby a man grieves for the delay of glory, is connected with the hindrance to a participation of the Divine good. _______________________
THIRD ARTICLE [II-II, Q. 28, Art. 3]
Whether the Spiritual Joy Which Proceeds from Charity, Can Be Filled?
Objection 1: It would seem that the spiritual joy which proceeds from charity cannot be filled. For the more we rejoice in God, the more is our joy in Him filled. But we can never rejoice in Him as much as it is meet that we should rejoice in God, since His goodness which is infinite, surpasses the creature's joy which is finite. Therefore joy in God can never be filled.
Obj. 2: Further, that which is filled cannot be increased. But the joy, even of the blessed, can be increased, since one's joy is greater than another's. Therefore joy in God cannot be filled in a creature.
Obj. 3: Further, comprehension seems to be nothing else than the fulness of knowledge. Now, just as the cognitive power of a creature is finite, so is its appetitive power. Since therefore God cannot be comprehended by any creature, it seems that no creature's joy in God can be filled.