When I visited the Sea of Galilee, I ate some of St. Peter’s Fish. It was quite delicious.
At the end of John’s Gospel, Peter drew a net full of 153 fishes to the shoreline.
You can tell that the early church fathers had the Trinity on their minds when they wrote things like this:
Cyril of Alexandria, followed by Ammonius, Euthymius, and Theophylact, “regards the number as being significant in its three simple elements: 100 + 50 + 3. The 100, he says, represents the fulness of the Gentiles, for 100 (=10 x 10) is ‘the fullest number,’ and as such it is used to describe the Lord’s full flock (Matt. xviii.12) and full fertility (Matt. xiii. 8). The 50 represents ‘the remnant of Israel according to election,’ which falls short of completeness (50 = 100/2). The 3 indicates the Holy Trinity, to whose glory all alike are gathered.”
Augustine “adopts a more complicated interpretation. Ten, he says, is the number of the Law. But the Law without grace kills. To the number of the Law therefore we add seven, the number of the Spirit, in order to obtain the fulness of the divine revelation as a power of life. But, he then adds, the sum of the numbers from one to seventeen inclusive is one hundred and fifty-three (1 + 2 + 3 &c. + 17 = 153). So that the number 153 signifies all those who are included in the saving operation of divine grace, which makes reconciliation with the Law. Nor is this all. The three is the symbol of the Trinity; and the triple fifty brings out the idea of unity in the Spirit, who is revealed in a sevenfold operation (50 = 7 x 7 + 1).”
Gregory the Great “adopts in part the symbolism of Augustine, but employs it even more ingeniously. The Evangelist, he writes, would not have given the exact number unless he had deemed that it contained a mystery. All action under the Old Testament is ruled by the Decalogue; and under the New Testament by the seven gifts of the Spirit (Isai. xi. 2). Our action, therefore, under both aspects can be represented by 10 + 7. But it is by faith in the Holy Trinity that action is made effectual. We therefore multiply 17 by 3 and obtain the number 51, which expresses the idea of true rest, being unity added to the number of the year of jubilee. This symbol of rest (51) is again multiplied by three and we gain the result 153, the symbol of the elect citizens of the heavenly country, the final heirs of rest (‘Hom.’ xxiv. 4).”
source – B. F. Westcott
Hmm . . . I see the Triune God from the beginning to the end of John’s Gospel. It is one of the greatest books ever written to unveil Trinitarian glory.
But I do not see the Trinity in St. Peter’s Fish (chuckling).
If you are interested in the number 153, read the discussion by George R. Beasley-Murray in his commentary on John (pp. 401-404).
And for you mathematicians, I strongly encourage you to read chapter 13, “The 153 Fish and the Unity of the Fourth Gospel” in Richard Bauckham’s book, The Testimony of the Beloved Disciple: Narrative, History, and Theology in the Gospel of John (2007).