Cf. I, 12, 7, ad 1; I-II, 4, 3
Objection 1. It would seem that the dowry is the same as beatitude. For as appears from the definition of dowry (1), the dowry is "the everlasting adornment of body and soul in eternal happiness." Now the happiness of the soul is an adornment thereof. Therefore beatitude is a dowry.
Objection 2. Further, a dowry signifies something whereby the union of bride and bridegroom is rendered delightful. Now such is beatitude in the spiritual marriage. Therefore beatitude is a dowry.
Objection 3. Further, according to Augustine (In Ps. 92) vision is "the whole essence of beatitude." Now vision is accounted one of the dowries. Therefore beatitude is a dowry.
Objection 4. Further, fruition gives happiness. Now fruition is a dowry. Therefore a dowry gives happiness and thus beatitude is a dowry.
Objection 5. Further, according to Boethius (De Consol. iii), "beatitude is a state made perfect by the aggregate of all good things." Now the state of the blessed is perfected by the dowries. Therefore the dowries are part of beatitude.
On the contrary, The dowries are given without merits: whereas beatitude is not given, but is awarded in return for merits. Therefore beatitude is not a dowry.
Further, beatitude is one only, whereas the dowries are several. Therefore beatitude is not a dowry.
Further, beatitude is in man according to that which is principal in him (Ethic. x, 7): whereas a dowry is also appointed to the body. Therefore dowry and beatitude are not the same.
I answer that, There are two opinions on this question. For some say that beatitude and dowry are the same in reality but differ in aspect: because dowry regards the spiritual marriage between Christ and the soul, whereas beatitude does not. But seemingly this will not stand, since beatitude consists in an operation, whereas a dowry is not an operation, but a quality or disposition. Wherefore according to others it must be stated that beatitude and dowry differ even in reality, beatitude being the perfect operation itself by which the soul is united to God, while the dowries are habits or dispositions or any other qualities directed to this same perfect operation, so that they are directed to beatitude instead of being in it as parts thereof.
Reply to Objection 1. Beatitude, properly speaking, is not an adornment of the soul, but something resulting from the soul's adornment; since it is an operation, while its adornment is a certain comeliness of the blessed themselves.
Reply to Objection 2. Beatitude is not directed to the union but is the union itself of the soul with Christ. This union is by an operation, whereas the dowries are gifts disposing to this same union.
Reply to Objection 3. Vision may be taken in two ways. First, actually, i.e. for the act itself of vision; and thus vision is not a dowry, but beatitude itself. Secondly, it may be taken habitually, i.e. for the habit whereby this act is elicited, namely the clarity of glory, by which the soul is enlightened from above to see God: and thus it is a dowry and the principle of beatitude, but not beatitude itself. The same answer applies to Objection 4.
Reply to Objection 5. Beatitude is the sum of all goods not as though they were essential parts of beatitude, but as being in a way directed to beatitude, as stated above.
Source: Summa Theologica (New Advent)