Matthew Poole and continuators on Acts 26:24

24 And as he thus spake for himself, Festus said with a loud voice, Paul, thou art beside thy self: much learning doth make thee mad.

This was the Opinion of Festus concerning Paul, and such is the Opinion of carnal and worldly men concerning such as are truly Godly. As the Prophet which came to Iehu, was counted a mad Fellow, 2 Kings 9.11. and the friends of our Saviour thought him to be besides himself. Mark 3 21. and it cannot be otherwise. For good men, and bad men, have quite different Apprehensions concerning most things; and what one calls good, the other accounts evil; and what is Wisdom to the one, is madness to the other.

Much Study many times encreasing Melancholly, which a sedentary and thoughtful Life is most exposed unto. Paul is reckon'd to have been skilful in the Hebrew, Syriac; Greek, and Latine Tongues, to have been well read in the Poets; and certainly he was an excellent Orator, as appears all along in his Defence he made for his Doctrine, and his Life; but there was yet somewhat more than all this. Festus might feel a more than ordinary effect from Paul's words, and not knowing of the Spirit by which he spake, did attribute it to his learning, or madness, or to any thing but to the true cause of it.