Acts 8:13

Then[And] Simon himself believed also We can see from the history which follows that the belief here described was of a very imperfect nature. It perhaps amounted to no more than the conviction that in Philip was some power greater than his own. We have an example of a like imperfect belief described in like words in St John's Gospel (Acts 8:31), "Then said Jesus to those Jews which believedon him," and all that follows in the chapter shews that the belief which they professed was not enough to prevent them from plotting for Christ's death.

and when he was baptized, he continued with Philips and wondered[was amazed] St Luke's words imply that Simon was only wonder-struck at the sight of the works wrought by Philip, just as his own works had made the Samaritans to wonder.

beholding the miracles and signs which were done Better, beholding the signs and great miracles wrought. There is apparently a distinction intended by St Luke between the belief of the Samaritans and that of Simon. When they believed, it was the preaching and the glad tidings to which they most gave heed, but the verb used in this verse seems to paint Simon as one who gazed with wonder only on a sight which was beyond him to explain.