Thomas Aquinas

“ Christ's Passion is the cause of our ascending to heaven, properly speaking, by removing the hindrance which is sin, and also by way of merit: whereas Christ's Ascension is the direct cause of our ascension, as by beginning it in Him who is our Head, with whom the members must be united.
Reply to Objection 3: Christ by once ascending into heaven acquired for Himself and for us in perpetuity the right and worthiness of a heavenly dwelling-place; which worthiness suffers in no way, if, from some special dispensation, He sometimes comes down in body to earth ”

“ For just as He is said to be emptied, not by losing His fulness, but because He took our littleness upon Himself, so likewise He is said to have descended from heaven, not that He deserted heaven, but because He assumed human nature in unity of person. ”

“ Further, Christ's was an earthly body, like to ours. But it is contrary to the nature of an earthly body to be borne upwards. Moreover, what is moved contrary to its nature is nowise moved by its own power. Therefore Christ did not ascend to heaven by His own power. ”

“ It would seem that Christ did not ascend above all the heavens, for it is written (Ps. 10:5) : "The Lord is in His holy temple, the Lord's throne is in heaven." But what is in heaven is not above heaven. Therefore Christ did not ascend above all the heavens. ”

“ Further, in every place a body exists, since there is no such thing as a vacuum in nature. Therefore if no body obtains a higher place than a spirit in the order of natural bodies, then there will be no place above every spiritual creature. ”

“ As Christ is said to have risen by His own power, though He was raised to life by the power of the Father, since the Father's power is the same as the Son's; so also Christ ascended into heaven by His own power, and yet was raised up and taken up to heaven by the Father. ”

“ But whereas our dwelling-place is one of generation and corruption, the heavenly place is one of incorruption. And consequently it was not fitting that Christ should remain upon earth after the Resurrection; but it was fitting that He should ascend to heaven.
Reply to Objection 1: That which is best and possesses its good without movement is God Himself, because He is utterly unchangeable, according to Malachi 3:6: "I am the Lord, and I change not." But every creature is changeable in some respect, as is evident from Augustine (Gen. ad lit. viii) . ”

“ Thirdly, that being established in His heavenly seat as God and Lord, He might send down gifts upon men, according to Eph. 4:10: "He ascended above all the heavens, that He might fill all things," that is, "with His gifts," according to the gloss.
Reply to Objection 1: Christ's Ascension is the cause of our salvation by way not of merit, but of efficiency, as was stated above regarding His Resurrection ( [4324] Q [56] , A [1] , ad 3,4) . ”