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Definition.com
A Professional is a man who can do his job when he doesn't feel like it. An amateur is a man who can't do his job when he does feel like it.
Definition.com
The Professional is distinguished from the madman in this: a professional does as well as he can within what he has set out to do and a madman does exceptionally well at what he can't help doing.
Definition.com
The Professional is contrasted with the businessman in that for the professional, money making is incidental... for the businessman it is primary.
See also
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