Cassius Dio 77.11.1-2 (Xiph.):


A.D. 208: Severus... made a campaign against Britain, though he knew that he should not return. He knew this chiefly from the stars under which he had been born, for he had caused them to be painted on the ceilings of the rooms in the palace where he was wont to hold court, so that they were visible to all, with the exception of that portion of the sky which, as astrologers express it, "observed the hour" when he first saw the light; for this portion he had not depicted in the same way in both rooms. He knew his fate also by what he had heard from the seers; for a thunderbolt had struck a statue of his which stood near the gates through which he was intending to march out and look toward the road leading to his destination, and it had erased three letters from his name. For this reason, as the seers made clear, he did not return, but died in the third year. (Loeb trans.)