The letter seemed so unlike anything which could have been expected! As I analysed my impression, I saw that it consisted of two distinct phases. First, granting that Akeley had been sane before and was still sane, the indicated change in the situation itself was so swift and unthinkable. And secondly, the change in Akeley’s own manner, attitude, and language was so vastly beyond the normal or the predictable. The man’s whole personality seemed to have undergone an insidious mutation—a mutation so deep that one could scarcely reconcile his two aspects with the supposition that both represented equal sanity. Word-choice, spelling—all were subtly different. And with my academic sensitiveness to prose style, I could trace profound divergences in his commonest reactions and rhythm-responses. Certainly, the emotional cataclysm or revelation which could produce so radical an overturn must be an extreme one indeed! Yet in another way the letter seemed quite characteristic of Akeley. The same old passion for infinity—the same old scholarly inquisitiveness. I could not a moment—or more than a moment—credit the idea of spuriousness or malign substitution. Did not the invitation—the willingness to have me test the truth of the letter in person—prove its genuineness?