What is the vine, more than another tree?
Nay most, than it, more tall, more comely be.
What workman thence will take a beam or pin,
To make ought which may be delighted in?
Its excellency in its fruit doth lie:
A fruitless vine, it is not worth a fly.
Comparison.
What are professors more than other men?
Nothing at all. Nay, there's not one in ten,
Either for wealth, or wit, that may compare,
In many things, with some that carnal are.
Good are they, if they mortify their sin,
But without that, they are not worth a pin.
John Bunyan
http://www.poemhunter.com/poem/upon-the-vine-tree/