The same dealt subtilly with our kindred, and evil entreated our fathers, so that they cast out their young children, to the end they might not live. The same dealt subtilty - Οὑτος κατασοφισαμενος, A word borrowed from the Septuagint, who thus translate the Hebrew נהחכמה לו nithchokmah lo, let us deal wisely with it, i.e. with cunning and deceit, as the Greek word implies; and which is evidently intended by the Hebrew. See Genesis 27:35, Thy brother came with subtilty, which the Targumist explains by בחוכמא be-chokma, with wisdom, that is, cunning and deceit. For this the Egyptians were so remarkable that αιγυπτιαζειν, to Egyptize, signified to act cunningly, and to use wicked devices. Hence the Jews compared them to foxes; and it is of them that Canticles, Sol 2:15, is understood by the rabbins: Take us the little foxes which spoil our vines; destroy the Egyptians, who, having slain our male children, sought to destroy the name of Israel from the face of the earth.
To the end they might not live - Might not grow up and propagate, and thus build up the Hebrew nation.