"It has been commented upon that the “Fundamental theorem of algebra” is not really fundamental, that it is not necessarily a theorem since sometimes it serves as a definition, and that in its classical form it is not a result from algebra, but rather from analysis."
"The essence of mathematics is proving theorems and so, that is what mathematicians do: they prove theorems. But to tell the truth, what they really want to prove, once in their lifetime, is a Lemma, like the one by Fatou in analysis, the Lemma of Gauss in number theory, or the Burnside-Frobenius Lem"
"For this end we verify the recursion F0 * F1 * … Fn-1 = Fn - 2 ( n >= 1), from which our assertion follows immediately. Indeed, if m is a divisor of, say, Fk and Fn (k<n), then m divides 2, and hence m = 1 or 2."