I was reminded of the quotation that may have been attributed to Einstein:
in reply to Second rate programmers and my confession
If I have seen further that anyone else, it is only because I was standing on the shoulders of giants.
Of course, I have probably not got the wording exact. But what he ws saying (assuming it was Einstein), is that our knowledge / expertise / whatever is built upon that of others.
What Ovid is saying about one's skills is very true. I thouhg I was a good racing sailor until I started to race on offshore boats. After two years on one boat, I moved to a larger, faster boat. With each change in environment, my skills improved dramatically.
Update: As a number have said, it was Issac Newton who said the above statement. Maybe Einstein said it as well, since by his time there were many more giants whose shoulders he could have stood on.