John Trapp on Matthew 16:21

Verse 21. How that he must go to Jerusalem] He must, necessitate non simplici, sed ex supposito. It being supposed that God had decreed this way (and no other) to glorifie himself in mans salvation by the death of his dear Son (wherein the naked bowels of his [illegible: 1 word] were laid open to us, as in an anatomy) it was necessary that Christ should be killed and raised again at the third day, Voluntu Dei, necessitas rei. And be killed and raised again] That we might live and raign with him for ever, who else had been killed with death, as the [illegible: 1 word] is, Rev. 2. 23. that is, had come under the [illegible: 1 word] of the second death. David wished he might have died for Absolom, such was his love to him. Arsinoe interposed her self between the [illegible: 1 word] weapons, sent by [illegible: 1 word] her brother, to kill her children. The [illegible: 1 word] not only feeds her young with her own bloud, but with invincible constancy abides the flames of fire for their preservation. Christ is that good shepherd, who gave his life for his [illegible: 1 word]. He is that true Pellican, who saw the wrath of God burning about his young ones, and cast himself into the midst thereof, that he might quench it. He was delivered for our offences, and was raised again for our justification, which began in his death, butRom. 4 25. was perfected by his resurrection.