Insofar as he makes use of his healthy senses, man himself is the best and most exact scientific instrument possible. The greatest misfortune of modern physics is that its experiments have been set apart from man, as it were, physics refuses to recognize nature in anything not shown by artificial instruments, and even uses this as a measure of its accomplishments.
There once was a Bald Man who sat down after work on a hot summer's day. A Fly came up and kept buzzing about his bald pate, and stinging him from time to time. The Man aimed a blow at his little enemy, but - whack - his palm come on his own head instead; again the Fly tormented him, but this time the Man was wiser and said: YOU WILL ONLY INJURE YOURSELF IF YOU TAKE NOTICE OF DISPICABLE ENEMIES.
Hopefully with each thing that you do you're learning something, you're growing, and you're pushing yourself a little harder in some way or another. So I think you'd be in real trouble if each new thing that you create didn't feel like 'Oh, wow. I feel like I'm doing something a little different this time.'