There lurks in most modern minds the notion that to desire our own good and earnestly to hope for the enjoyment of it is a bad thing.
Is this "earnestly" an adverb? If it is, then why "earnestly to hope"? Shouldn't there be no "to" in between the adverb and the verb it modifies?
The original sentence is:
If there lurks in most modern minds the notion that to desire our own good and earnestly to hope for the enjoyment of it is a bad thing, I submit that this notion has crept in from Kant and the Stoics and is no part of the Christian faith.
Lewis, C. S.. Weight of Glory (Collected Letters of C.S. Lewis) (p. 27). HarperCollins. Kindle Edition.