According to Wikipedia, "the first fundamental theorem of calculus shows that an indefinite integration can be reversed by a differentiation." Am I wrong or is this theorem very simple? Indefinite integrals are the same as antiderivatives. So isn't this theorem simply stating that the derivative of the antiderivative of a function is the function itself? But this already follows from the definition of antiderivatives itself! So isn't this theorem simply a re-statement of the definition of antiderivatives?