"Flesh and blood, that is, the body sown in corruption (v. 42), the natural body (v. 44), image of the earthly Adam (v. 49). It is not the substance of flesh and blood that is excluded from heaven, but their mortal accidents, bodily needs, and passions thence resulting. Corruption here means the corruptible body, as such, with all the train of evils attendant thereupon, both moral evils, which go by the name of the flesh in the bad sense of that term, and more particularly, the physical frailty and perishableness of our mortal frame." Notes on St Paul in h.l.
Of God and His Creatures: 4.85