NET
24 As Paul was saying these things in his defense, Festus exclaimed loudly, “You have lost your mind, Paul! Your great learning is driving you insane!”
Darby
24 And as he answered for his defence with these things, Festus says with a loud voice, Thou art mad, Paul; much learning turns thee to madness.
KJV
24 And as he thus spake for himself, Festus said with a loud voice, Paul, thou art beside thyself; much learning doth make thee mad.