William Secker says - (Unnatural vs. Supernatural)

"It is unnatural to hate them that love us; and it is supernatural to love them that hate us."
The Nonsuch Professor p.58

For if ye love them which love you, what thank have ye? for sinners also love those that love them. But love ye your enemies, and do good, and lend, hoping for nothing again;

Luke 6:32,35