It is interesting to note that in Helvering v. Davis, the phrase "general Welfare of the United States" does not appear. The only term used is "general welfare".
Just to keep my hand in the thread till I have time to get back to the discussion, I thought I'd drop this into the mix. It is from a question/answer session following a speech, On Interpreting The Constitution, Justice Scalia delivered in 1997 before The Manhattan Institute For Policy Research. If you have time, take a look. Try to decide whether or not he was making a joke. Plenty in there to agitate both liberals and conservatives.
MALE VOICE: No, I'm talking about the power; the legitimacy of the Federal Government to undertake actions to say control how your children are raised.
I would suggest the Federal Government does not have that power because that power is not enumerated in The Constitution. And that's why the framers (talking away from microphone)
JUSTICE SCALIA: Okay. I mean, yes. I mean, another reason why some things can't be done by the Federal Government is that there is no proper Federal power.
But I suppose the Federal Government could fund, under its power; its welfare power, could fund Federal schools. And prescribe the programs for Federal schools. And then say you must go to Federal schools.