{As he thus made his defence} (	auta autou
apologoumenou). Genitive absolute again with present middle
participle. Paul was still speaking when Festus interrupted him
in great excitement. {With a loud voice} (megal(8869) t(8869) ph(936e)(8869)).
Associative instrumental case showing manner (Robertson,
_Grammar_, p. 530) and the predicate use of the adjective, "with
the voice loud" (elevated). {Thou art mad} (main(8869)). Old verb
for raving. See also  Joh 10:20  Ac 12:15  1Co 14:23 . The
enthusiasm of Paul was too much for Festus and then he had spoken
of visions and resurrection from the dead (verse  8 ). "Thou art
going mad" (linear present), Festus means. {Thy much learning
doth turn thee to madness} (	a polla se grammata eis manian
peritrepei). "Is turning thee round." Old verb peritrep(935c), but
only here in N.T. Festus thought that Paul's "much learning"
(="many letters," cf.  Joh 7:15  of Jesus) of the Hebrew
Scriptures to which he had referred was turning his head to
madness (wheels in his head) and he was going mad right before
them all. The old word mania (our mania, frenzy, cf. maniac)
occurs here only in N.T. Note unusual position of se between
polla and grammata (Robertson, _Grammar_, pp. 418, 420)