Charles Spurgeon Commentary Acts 8:31-34

"And he said, How can I, except some one shall guide me? And he besought Philip to come up and sit with him. Now the passage of the Scripture which he was reading was this, He was led as a sheep to the slaughter; And as a lamb before his shearer is dumb, So he openeth not his mouth: In his humiliation his judgment was taken away: His generation who shall declare? For his life is taken from the earth. And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other?" — Acts 8:31-34 (ASV)

And he said, How can I, except some man should guide me?

And he desired Philip that he would come up and sit with him. The place of the scripture which he read was this, He was led as a sheep to the slaughter; and like a lamb dumb before his shearer, so opened he not his mouth: in his humiliation his judgment was taken away: and who shall declare his generation? for his life is taken from the earth. And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other man?

That was a very important question; it went to the very root of the matter. It was useless for him to read about some unknown person; he had to know who it was about whom the prophet had written.