Previously unavailable correspondence between Niels Bohr, his fiancée and his family, together with published yet unexploited Danish sources, now allows us to present a more detailed account than previously possible of the creation of the quantum atom. Owing to the undeveloped state of the psychology of invention, however, the account can only resemble an electron jump between well-defined states; the transition between them eludes description. The present attempt begins with an inventory of the "initial state", that is, the relevant content of Bohr's mind when he began working on the nuclear atom in the summer of 1912; continues with the inputs that stimulated the transition to his quantum atom early in 1913; and concludes with a description of the "end state", the theory of the hydrogen spectrum and the remarkably revealing, contradictory justifications that Bohr initially offered to secure it. Observations on creativity in general round out the text.