The maxim that concludes Peirce's 1903 Harvard lectures on pragmatism is not a figurative restatement of his 1878 pragmatic maxim: it adds to it a non-verificationist dimension of meaning. That addition is required to defend as meaningful the modal realism that the 1878 maxim presupposes but for the meaning of which it cannot itself account. The 1903 maxim grounds Peirce's late, phenomenological project of tracing metaphysical categories to their sources in experience. To arrive at these conclusions, some time is first taken with a reading of the 1878 maxim.