13. For the promotion of Gallus see Idatius, Zosimus, and
the two Victors. According to Philostorgius (1. iv. c. 1 ),
Theophilus, an Arian bishop, was the witness, and, as it
were, the guarantee of this solemn engagement. He supported
that character with generous firmness; but M. de Tillemont
(Hist. des Empereurs, tom. iv. p. 1 1 20) thinks it very
improbable that a heretic should have possessed such virtue.