it. i.e. Christ. The corruption of this in the Vulgate into "she" lies at the root of Mariolatry: the verb in singular. Masculine shows that zer'a (seed) is here to be taken in singular, with Septuagint, i.e. Christ; see note on Gen_17:7; Gen_21:12, and Gal_1:3, Gal_1:16.
head . . . heel. See App-19. No more literal than 1Co_11:8, or Psa_41:9, and Joh_13:18. They denote the temporary sufferings of the Seed, and the complete destruction of Satan and his works (Heb_2:14. 1Jn_3:8). Heel = lower part. Head = vital part. This is the first great promise and prophecy. Note its position in the centre of Structure above.