No one need blindly follow this theory of mine as though it were quite
perfect, for human nature has not yet so far degenerated that another
man cannot discover something better. So each may use my teaching as
long as it seems good to him, or until he finds something better. Where
he is not willing to accept it, he may well hold that this doctrine is
not written for him, but for others who are willing.

That must be a strangely dull head which never trusts itself to find out
anything fresh, but only travels along the old path, simply following
others and not daring to reflect for itself. For it beseems each
understanding, in following another, not to despair of itself
discovering something better. If that is done, there remaineth no doubt
but that in time this art will again reach the perfection it attained
amongst the ancients.

Much will hereafter be written about subjects and refinements of
painting. Sure am I that many notable men will arise, all of whom will
write both well and better about this art, and will teach it better than
I; for I myself hold my art at a very mean value, for I know what my
faults are. Let every man therefore strive to better these my errors
according to his powers. Would to God it were possible for me to see the
work and art of the mighty masters to come, who are yet unborn, for I
know that I might be improved upon. Ah! how often in my sleep do I
behold great works of art and beautiful things, the like whereof never
appear to me awake, but so soon as I awake, even the remembrance of
them leaveth me.

Compare also the passages already quoted,(pp. 15,16,26).