John Wesley on Daniel 7:6

Like a leopard - This leopard was the Grecian monarchy; a leopard is less than a lion, so was this monarchy at first, but yet durst fight with a lion; so did Alexander encounter Darius with an inferior force. A leopard also for his swiftness; therefore described with four wings on his back. Four heads - He was succeeded by four of his chief commanders, who divided that empire into four parts.