The icon for Mid-Pentecost does not show Christ teaching in the temple in the middle of the feast (John 7:14-53) but as a youth (Luke 2:41-50).
It intends to bring to mind Christ as the pre-incarnate Logos (Emmanuel; Angel of Great Counsel), depicted as a beardless youth.
Today we hear Christ in the temple promising the Water of Life, we recall His teaching as a youth, and we recognize Him as the Holy Wisdom of God.
Therefore, Churches named 'Holy Wisdom' celebrate on Mid-Pentecost.
Let us learn, be in-formed, by this song:
"See where the amaranth grows, it grows amidst the δύσβατα (hard-to-tread)" == ἄβατον (not-to-be-trod, i.e. sacred).