In June of 2017 former FBI director James Comey appeared before Congress to testify about his firing by Donald Trump,. Republican Senators closed ranks and tried to mount an assault on his credibility. When it came time for John McCain to do his part, he stumbled badly over his words and became confused, asking a series of absurdly incoherent questions.

Just one year earlier I had seen McCain speak at an event in Singapore, and he was sharp as a tack. Misguided in his beliefs about foreign policy, perhaps, but his command of the facts and the substance and his easy-going wit were clear as day. “What will happen if Donald Trump wins the election?” someone in the audience asked him as he had recently been embroiled in some verbal spats with Trump around that time, and it was clear, even in Singapore, that they despised one another. Without missing a beat, McCain sardonically replied: “I don’t know. But whatever happens, I’m sure it’s going to be great” and he put just a little bit of extra english on the word great. The room erupted in laughter.

12 months later and here he was in the Capitol unable to grasp basic facts or craft a single coherent sentence. Something was clearly wrong with him, and it was impacting his mental functions. This turned out to be a malignant brain tumor, which claimed his life the following year. But for the grace of God’s light, ultimately no one can escape the pull of time and age. It takes its toll on people, and though it’s a sensitive topic that makes us uncomfortable to discuss, it is especially relevant when it comes to elected officials or others holding important positions of power. Just look at Bob Mueller’s performance before Congress earlier this year. The man, through no fault of his own, has obviously been slowed by the entropic arrow of time and he struggled to field complex questions related to his investigation.

For Democrats, Biden is the nation’s grandpa. He’s charming in his old-timey way, his life story makes him a sympathetic figure and more importantly he reminds us of a time that seems almost ancient now, when the President was a man of dignity, intellect and honor. This has endeared him, at least in these early stages, to many centrist voters. But age has clearly taken its toll on Joe Biden, and this is both hugely important and not something we can ignore. This has nothing to do with policy. It’s about his basic fitness for office. He fumbles questions and becomes easily confused; he has lost a step, and sadly it’s not a step he is ever going to regain. He is likely to lose a few more before it’s all said and done.

I loved my grandpa dearly. When I was a teenager I would go to his house in the summer time and paint the eaves for $6 an hour, then sit on the couch and watch Zaboomafoo on Nickelodeon with him, for despite being a Marine who landed on Guam during World War II he always remained a kid at heart. He would doze off in the sultry afternoon heat while the hummingbirds licked the feeders hanging over the patio.

Being around him in those days made me feel comfortable and it would remind me of the good times from my childhood when he dressed up like Santa or took us on a weekend trip to Mexico. But he was clearly in the twilight of his life at that point, and would become easily confused trying to do simple things like dial a telephone number. I don’t say this in a pejorative way but as a simple statement of fact: he was not capable of being entrusted at that point with any great or demanding responsibility. His duty, and that of all of us lucky enough to have the luxury, was to enjoy his final years on this Earth without placing an undue burden on himself.

If Biden were to be the Democratic candidate for president, he would be placing an undue burden on himself and on the nation. It is abundantly clear that he is not mentally fit to bear the great burden and responsibility of being president of the United States. Let’s be clear - this is not his fault. He is not afflicted with an internal rot like Donald Trump, who has always been a despicable person. He is simply experiencing the gradual erosion of his mental faculties due to the effects of aging. This much is clear. And it’s equally clear, and should be even more obvious nowadays, that we cannot elect people to office who are unfit for the role.

I loved my grandpa dearly. But grandpa couldn’t be President of the United States of America, and neither can Joe Biden.