The Headmistress was as surprised as Poppy to see Albus Dumbledore in the Hospital wing. The old Headmaster was looking very… subdued.
Without waiting for any distracting greetings or pleasantries, the Healer said, "We need to talk."
She looked sternly at Dumbledore. "First off, Albus, how long have you known?"
"I suspected that my… reasoning, wasn't what it once was ten years ago."
"And that's when you started self-potioning?"
The old man nodded, "It helped, for a while. For a fair, few years."
Poppy turned to Minerva, "Professor Dumbledore is suffering from Senile Dementia, he can no longer be expected to head a school. He may be well enough, for a time, to teach - four or five years, perhaps. But his condition, from now on, will need to be reviewed every six months."
Albus smiled wryly, "This year, I could teach Potions or Runes, but not after next year. Indeed, as my capacity diminishes, I can see myself, in twenty more years, as the Keeper of Keys and Grounds."
The horror of Dumbledore's condition was driven home as the old man sobbed, "I may have done more damage already than can be undone. I simply don't know what I don't know."
And it all became clear. Leaving the Potters, as bait, for Voldemort to find. Packing Harry off to his murderous relatives. Bringing the Philosopher's Stone to the Castle, again, as bait for Voldemort. Foisting more and more of the responsibilities for running the premier magical academy in the United Kingdom on his Deputy.
And worse, doubting more and more, every day, if he were making the right choices, if he could make the right choices for… everyone!
Minerva put her arm around her old mentor, "You will finish this year as Headmaster, just be sure to continue leaving all the decision-making to me. We will inform the Board of Governors, who will, I'm sure, agree to allow you to retire, gracefully, as Headmaster, and, perhaps, continue in some advisory capacity.
Grateful tears streaming down his whiskered face, Albus Dumbledore nodded.