The line is almost certainly one Hemingway never thought would become famous. Here it is, dialogue from The Sun Also Rises."
"How did you go bankrupt?" Bill asked.
"Two ways," Mike said. "Gradually and then suddenly."
You grow old the same way: first slowly, then all at once.
What does it mean to be old? I recall a woman of my mother's generation saying, when she lost a younger friend, "I'm afraid I'll grow old now!" She was around seventy then, so I thought privately, but she is old. I came to think that to her, "old" meant she would lose the spontenaiety and fun her friend had brought to her life.
To grow old is to lose without any choice in the matter particular friends, faculties, abilities, dreams, illusions. Sometimes you lose something quite suddenly: a bone in your foot breaks for no good reason, just standing around in tight shoes. It is your driving foot, and you're grounded for weeks. That will pass, but it can happen again. Now you have to wear good shoes, ugly old lady shoes with orthotics. You will nevertheless get more stress fractures.
You have lost more than your wardrobe. You have grown aware of a fragility you never thought you had. You have learned, maybe, that you have no idea what your vulnerabilities are, what you will lose next.
As for the picture, it is found art. I had been sharpening my colored pencils, and suddenly saw the paper where the shavings had fallen. I filed it under "abstractions." The ability to see beauty in unexpected places has perhaps an accidental and tenuous connection to my subject today.