‘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 opens not his mouth. In his humiliation his judgment was taken away. His generation who shall declare? For his life is taken from the earth.” '
The passage he was reading came from Isaiah 53 LXX, the main chapter about the Suffering Servant. To seek, as some have done, to rid this quotation of its sacrificial significance is frankly incredible. A lamb led to the slaughter in the context of Isaiah 53 would for any Christian be a sacrificial lamb (compare John 1:29; 1 Corinthians 5:7). And all lambs led to the slaughter within the vicinity of Jerusalem had to be offered on the altar. Besides these were simply the verses that Philip heard him reading. Prior to Philip's approach he would have read the previous verses. It is so extremely unlikely as to be impossible that in the context Philip would only expound on the verses he had heard him read, and avoid mentioning the verses he had previously read.
In context the picture expressed here is of One spoken of as being led like a sacrificial lamb to His death, having been wrongly judged, but silent like a sheep before his shearers in the face of his humiliation, with the result that His life was taken from the earth. And in the context this both refers back to His sufferings on behalf of ‘us' (Isaiah 53:4-5) and His having laid on Him the iniquity of us all (Isaiah 53:6), and forward to His being made a guilt offering for sin (Isaiah 53:10). Scholars and the Ethiopian official may have had difficulty with these verses but we doubt whether either Philip or Luke had (see Luke 22:37).