Amongst the objections to the formalisation of logic and mathematics, one of the most common consists in asserting that such a formalisation would reduce logical and mathematical thought to purely mechanical operations, and would thus allow the construction of a "thinking machine" capable of replacing the logician and the mathematician. The acceptance of the possibility of such a replacement would force us to deny all originality to logical and mathematical thought, and it would thus be incompatible with our experience according to which the solution of mathematical problems, in particular, requires original thought.