Matthew 10:16

ὡς πρόβατα ἐν μέσῳ λύκων] Clemens Rom. (II. 5), who quotes these words, adds to them: ἀποκριθεὶς δὲ ὁ Πέτρος αὐτῷ λέγει, Ἐὰν οὖν διασπαράξωσιν οἱ λύκοι τὰ�; Εἶπεν ὁ Ἰησοῦς τῷ Πέτρῳ, Μὴ φοβείσθωσαν τὰ�.

φρόνιμοι … ἀκέραιοι. The qualities required for the safety of the unarmed traveller. Prudence and simplicity are the defence of the weak. φρόνιμοι = ‘prudent,’ full of precaution, possessing such ‘practical wisdom’ as Paul had when he claimed the rights of Roman citizenship at Philippi. But the wisdom of a serpent is often to escape notice. With this thought the etymology of ὄφις agrees, whether it is the ‘seeing creature’ (οπ- as in ὄπωπα) quick to discern danger, or ‘the creature that hides’ (ὀπή, a hole). Comp. the expression in Romans 16:19, θέλω δὲ ὑμᾶς σοφοὺς εἶναι εἰς τὸ�, ἀκεραίους δὲ εἰς τὸ κακόν, and note the change from φρόνιμοι of the text to σοφούς, denoting intellectual discernment of the good. The difference in the directions precisely meets the difference of the two occasions. ἀκέραιοι (κεράννυμι) means unmixed, so ‘pure,’ ‘simple,’ ‘sincere,’ not ‘harmless,’ as in A.V. The disciples who were ‘simple’ as doves might hope to share the immunity of doves. Tibullus says (I. 7. 17):

Quid referam ut volitet crebras intacta per urbes Alba Palestino sancta columba Syro.

The epithet alba helps to explain ἀκέραιοι.