St. Thomas Aquinas
“The breaking of the host denotes three things: first, the rending of Christ’s body, which took place in the Passion; secondly, the distinction of His mystical body according to its various states; and thirdly, the distribution of the graces which flow from Christ’s Passion, as Dionysius observes (Eccl. Hier. iii). Hence this breaking does not imply severance in Christ.”
Source: St. Thomas Aquinas, Summa Theologica