Two notes here that I think are very important. First, while that quote of James Madison is correct, it was a) not the last word on the subject (in fact, he lost the argument to Hamilton, who "argued for a broad interpretation which viewed spending as an enumerated power Congress could exercise independently to benefit the general welfare.
Madison wrote the general Welfare clause, therefore it is his comments on it should be how it is interpreted. That the Butler decision chose to use Hamilton's opinion
of it and not what Madison intended it to be makes the decision of questionable Constitutional validity. The Butler decision was made during the New Deal which when FDR ignored our Constitution.