Not in persuasive words of wisdom (ouk en piqoi sopia logoi). This looks like a false disclaimer or mock modesty, for surely the preacher desires to be persuasive. This adjective piqo (MSS. peiqo) has not yet been found elsewhere. It seems to be formed directly from peiqw, to persuade, as peido (pido) is from peidomai, to spare. The old Greek form piqano is common enough and is used by Josephus (Ant. VIII. 9. 1) of "the plausible words of the lying prophet" in 1 Kings 13:1 ff. The kindred word piqanologia occurs in Colossians 2:4 for the specious and plausible Gnostic philosophers. And gullible people are easy marks for these plausible pulpiteers. Corinth put a premium on the veneer of false rhetoric and thin thinking. But in demonstration (all en apodeixei). In contrast with the plausibility just mentioned. This word, though an old one from apodeiknumi, to show forth, occurs nowhere else in the New Testament. Spirit (pneuma) here can be the Holy Spirit or inward spirit as opposed to superficial expression and power (dunami) is moral power rather than intellectual acuteness (cf. Colossians 1:18 ).