John Calvin Commentary 1 Peter 3:4

"but [let it be] the hidden man of the heart, in the incorruptible [apparel] of a meek and quiet spirit, which is in the sight of God of great price." — 1 Peter 3:4 (ASV)

But let it be the hidden, man of the heart. The contrast here should be carefully observed. Cato said that those who are anxiously engaged in adorning the body neglect the adorning of the mind. So Peter, to restrain this desire in women, introduces a remedy: that they are to devote themselves to the cultivation of their minds.

The word heart, undoubtedly means the whole soul. He at the same time shows in what the spiritual adorning of women consists: namely, in the incorruptness of a meek and quiet spirit. “Incorruptness,” as I think, is set in opposition to things that fade and vanish away—things that serve to adorn the body. Therefore, the version of Erasmus departs from the real meaning. In short, Peter means that the ornament of the soul is not like a fading flower, nor does it consist in vanishing splendor, but is incorruptible.

By mentioning quiet and a tranquil spirit, he marks out what especially belongs to women, for nothing suits them more than a placid and sedate temper of mind. For we know how outrageous an imperious and self-willed woman can be. Furthermore, nothing is more fitted to correct the vanity of which Peter speaks than a placid quietness of spirit.

What follows—that it is in the sight of God of great price,—may be referred to the whole previous sentence as well as to the word spirit; the meaning indeed will remain the same. For why do women take so much care to adorn themselves, except to turn the eyes of men on themselves? But Peter, on the contrary, bids them to be more anxious for what is before God of great price.