Max, a calico guinea pig, was adopted as the family pet circa 1968, a few years after we lost the wildly likeable white rabbit we called Mr. K. I still don’t know how on earth my father, a military man, conceded to the string of non-traditional pets — Ping, the duck; Cocoa and Nosey, the first set of house-trained rabbits; K; and finally, Max — except that maybe in Ping, who actually adopted us, he saw the promise of new and unexpected behavior, which spoke directly to his heart.(In brief, Ping was left behind by his mother and imprinted on us. Would not go swimming in Lake Washington without us. Followed us as if we were his six-duck family. Would only sleep with the radio on. And might have taught us all quite a bit more about the true nature of bonding had he not ingested something deadly in the backyard one night.)It never occurred to us — despite the prevailing attitudes towards rodents — to put Max in a cage. He was given wood crates in the kitchen and pantry and allowed to roam freely between them — and anywhere else in the house, if he so chose. To get around the kitchen, he would stick close to the walls, a bullet-shaped Pac-Man, always taking the same safe path to get to the same safe spot — except when mysteriously and unexpectedly driven to risk wide open flooring.

Max was a diminutive tenant in a very large house. Although he did not physically grow to fit his space — like the goldfish in our pond did — he was asked to stretch his spirit and behavior, to respond to the towering giants around him and try new things. We spoiled him with rose petals, clover and his baffling favorite, the cover of TV Guide (the chewing of which could be heard across a room like a typewriter).

Of course, he exhibited the typical piggie behaviors — the “wheeking,” the noisy shudders, the happy jumping. He wheeked to the sound of the refrigerator door opening, but also to our calling his name. At night in front of the TV, even my dad would take a turn holding him. But only my brother Eric could get Max to flip onto his back, trust his human keeper enough for a belly rub.

When Max died of pneumonia, shortly after our return from vacation one summer, the vet told my mother — who was devastated by the news — that he thought our Maximilian really had died of a broken heart, having been lost without his people, the love, the stimulation, the learning curve.

As the days get shorter, darker, and colder — a natural time for us to venture in and within — I’m thinking about Max, his small testimonials to neuroplasticity, and our own tendencies the other way, toward habitual behaviors. Those grooves and ruts, the things we defend as time saving and efficient and easy and comfortable — even graceful. Especially as we age, we are prone to ask exactly what the harm is in routine.

What is the harm in swinging my legs out of the same side of the bed every morning, while having the same kinds of thoughts I always have as my feet touch the floor? What is the harm in sitting in the same chair for my morning toast and coffee, looking through the same window at the same view? It’s my ritual, can’t I keep it sacred, for Pete’s sake? Is it hurting anyone?

It may be hurting you. One of the fundamental concepts of neuroplasticity is that connections in the brain are constantly being “pruned” and neural pathways rechanneled and recreated. This means that by new behaviors and thoughts we can forge new and healthier pathways — despite shrinking numbers of neurons. That with new pathways we actually change the form and functioning of the nervous system itself. We stretch it. We grow it. We risk wide open flooring to get to a more interesting room.

The real question is what, exactly, will snatch us from our narrow and narrowing grooves, the gray-matter paths we tread with the shoes of habitual thought and action? A vague sense of atrophy? Of rigidity? A yearning for freedom, flexibility and cannier engagement in the present moment?

Or, in a moment of grace and neuroplasticity, will we eat breakfast in bed one day, look up from our cheese omelet, and realize just how beautiful — and liberating — the view is?