His head and his hairs were white like wool, as white as snow; and his eyes were as a flame of fire;
Greek, 'But.'
Like wool - Greek, 'like white wool.' The colour is the point of comparison: signifying lovely purity. So in Isaiah 1:18. Not age; for hoary hairs indicate decay. Still, He is "the ancient of days" (Daniel 7:9).
Eyes were as a flame - all-searching, penetrating like fire; also, consuming indignation against sin, especially at His coming "in flaming fire, taking vengeance" on all the ungodly. Confirmed by Revelation 19:11-12.