As Paul recollected his conversion and baptizm, he tells how he was told, "And now what are you waiting for? Get up, be baptized, and have your sins washed away, calling on his name" (Acts 22:16, NET). "Be baptized" is an aorist middle imperative, which can be taken as "permissible middle," where the subject allows an action to be done in behalf of self or allow to take place" or as a "direct middle," acting on himself, in this case, baptizing himself. But we have the practice of proselyte baptism, which was self-administered. Is this a possible backdrop? But then we have Acts 9:18, which have "be baptized" as an aorist passive indicative. Elsewhere the passive has the sense of the middle (1 Pet.5:6). Is this the case here?