Perhaps; but that is an interpretation superimposed at a later time; and after MacMillan's death, so we cannot ask him what his intention might have been. Certainly, a great many people would assume that meaning (as evidenced by earlier contributions to this rather old thread), but the fact remains that, if that is indeed the case, it is a modern slant wished upon an old song that, as Aodh has explained, actually dealt with a quite different time and experience.