Mine just this one chapter for examples and you find them aplenty:

"I have seen a great many lists of her drawing up at various times of books that she meant to read regularly through -- and very good lists they were -- very well chosen, and very neatly arranged -- sometimes alphabetically, and sometimes by some other rule. The list she drew up when only fourteen -- I remember thinking it did her judgment so much credit, that I preserved it some time...

At ten years old, she had the misfortune of being able to answer questions which puzzled her sister at seventeen. She was always quick and assured..."

"...I shall not attempt to deny Emma's being pretty."

"...I confess that I have seldom seen a face or figure more pleasing to me than her's."

"I have not a fault to find with her person," he replied. "I think her all you describe. I love to look at her; and I will add this praise, that I do not think her personally vain. Considering how very handsome she is, she appears to be little occupied with it...

He seems to have been paying Emma a great deal of attention for much of the last ten years. Even if he isn't aware of where his feelings are leading him when he says these things, I think it's clear that he could look back a year later and realize that he had been captivated by Emma for a very long time.