Perish with thee (sun soi eih ei apwleian). Literally, Be with thee for destruction. Optative for a future wish. The use of ei with the accusative in the predicate is especially common in the LXX. The wish reveals Peter's indignation at the base offer of Simon. Peter was no grafter to accept money for spiritual power. He spurned the temptation. The natural meaning of Peter's language is that Simon was on the road to destruction. It is a warning and almost a curse on him, though verse Acts 22 shows that there was still room for repentance. To obtain (ktasqai). To acquire. Usual meaning of the present tense (infinitive middle) of ktaomai.