In Revelation 10:1, the reason why the Lord's feet seemed to be 'pillars of fire,' is because the Lord's Divinity on the natural plane -- which fundamentally is the Divine humanity that He took on in the world -- supports His Divinity from eternity, as the body does the soul, and likewise as the Word's natural meaning supports its spiritual and celestial meanings, for 'feet' signify natural things, 'pillars' signify support, and 'fire,' divine love.

(References: Apocalypse Explained 10; Apocalypse Revealed 468)