Stretch back to the 1st century BC, we find the following familiar quotes from Publilius Syrus, a Latin writer of mimes (thanks for the tip, Dave!):

• Never find your delight in another's misfortune.
• A rolling stone gathers no moss.
• Every day should be passed as if it were to be our last.
• No one knows what he can do till he tries.

Another, which provides an interesting perspective on modern day appraisal practices is "Everything is worth what its purchaser will pay for it."

While this may have been a prevailing theory at the time, modern day appraisal practice takes a bit of a different stance, more along the lines of "Everything is worth what someone else recently paid for something similar."

For example.... if three fine homes have recently sold for $325k, $330k and $335k, we'd probably all agree that a fourth similar home is probably worth around $330k.  But what if it a buyer and seller agree to a sales price of $345k?  The appraisal is likely going to come back low, closer to $330k.  But despite Past Buyers #1, #2 and #3 paying around $330k, if Current Buyer #4 wants to pay $345k, doesn't that mean that it some ways the house is indeed worth $345k??