The Hazel is the tree of wisdom.
Hazel nuts are concentrated wisdom, so by eating them, you'll become wise enough to not believe this kind of nonsense.

In Irish myth, the most ancient and wise of animals - Salmon - swam in the River Boyne under the Hazel tree from which the Nuts of Wisdom fell.
Salmon ate them and was in turn eaten by Finn MacCumhaill, who thus acquired infinite knowledge.
Which he used to form and lead a roving warband.
Real presidential material, that one.

The deity associated with hazel, is the god of writing, eloquence and poetry Oghma, a son of the Dagda and the goddess Danu (Yes, I know, but in the Era of the Gods there was no Moral Majority. Obviously. Fortunately).
His greatest merit was inventing the Ogham writing system and offering it to the druids.
Who didn't use it to elevate the people but as an magical instrument of power.
Of course.

Portrayed here is Oghma's Gallic counterpart, Ogmios. Traditionally, he should be wearing a lion's skin, which I interpreted rather literally. The chain that binds people by their ears to his tongue is a Roman invention.

The Ogham sign attributed to this month is Coll.