John the Apostle
Revelation 17:9ESV·traditional attribution

This calls for a mind with wisdom: the seven heads are seven mountains on which the woman is seated;

Matthew Henry Presbyterian @wholebiblehenry

Here we have the mystery of this vision explained. The apostle wonders at the sight of this woman: the angel undertakes to open this vision to him, it being the key of the former visions; and he tells the apostle what was meant by the beast on which the woman sat; but it is so explained as still to need further explanation. 1.

Commenting on Revelation 17:7-13

John Gill Reformed Baptist @doctorgill

And here is the mind which hath wisdom,.... This refers either to what goes before, concerning the beast, his various states, rise, and ruin, and his admirers; or to what follows after, concerning the meaning of his heads and horns, or to both; and the sense is, that notwithstanding the interpretation of these things by the angel, yet it requires a large share of wisdom...

Albert Barnes Presbyterian @notesbybarnes

Verse 9. And here is the mind which hath wisdom. Here is that which requires wisdom to interpret it; or, here is a case in which the mind that shows itself able to explain it will evince true sagacity. So in . . Prof.