Once the amateur's naive approach and humble willingness to learn fades away, the creative spirit of good photography dies with it. Every professional should remain always in his heart an amateur.
A pro only means you shoot for pay. As an amateur, I learned from pros. As a pro, I continue to learn from amateurs.
Usually the amateur is defines as an immature state of the artist: someone who cannot — or will not — achieve the mastery of a profession. But in the field of photographic practice, it is the amateur, on the contrary, who is the assumption of the professional: for it is he who stands closer to the (i)noeme(i) of Photography.