Mystically, in the draught of fishes He signified the mystery1 of the Church, such as it will be at the final resurrection of the dead. And to make this clearer, it is put near the end of the book. The number seven, which is the number of the disciples who were fishing, signifies the end of time; for time is counted by periods of seven days.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Tract. cxxii