My college roommate Jay, an Iowan, used to tell us that if you stand in a cornfield on a warm, quiet afternoon, you can hear the corn grow. I’m not sure how he knew this — he was from Council Bluffs, an honest-to-goodness city whose residents spend very little time in cornfields — but I have no reason to doubt him. A typical stalk of corn grows almost an inch per day, so it’s easy to imagine that those stiff, proliferating plant cells might make some sort of racket.

I think of that now because Debra and I — as we so often do — have been raising a litter of foster kittens. When they arrived from the city animal shelter, they were only a few days old. They looked like tiny mice, their eyes and ears still sealed, their legs wobbly. We had to bottle-feed them every three hours around the clock. We fretted about whether these fragile creatures would manage to survive without a mama cat to nurture them.

Well, it’s now two months later, and those mice have grown into healthy, affectionate, playful, and adorable kittens. They weigh more than five times what they did when they first arrived. Soon we’ll be returning them to the animal shelter, which will find a loving, permanent home for each of them. None of this is particularly remarkable; and yet I find myself wondering daily: How is this possible?

We used to watch these kittens latch onto a rubber nipple and suck down half a bottle of milk substitute without stopping for breath. Eventually they graduated to lapping up partly-solid gruel, and now they’re noisily feasting on juicy, brown paté spooned straight out of a can. Somehow, those nondescript foodstuffs routinely turned into more kitten. Each kitten’s weight increased by half an ounce or an ounce a day; now the daily weight gain is sometimes as much as two ounces.

I realize that growth is a pretty universal function for living things; we’ve all experienced it ourselves. What makes it feel so miraculous in this case is that it happens so quickly — from a little mound of fluff that fits in the palm of the hand to a fully-formed animal, all in the space of a few weeks. Every time I look at or hold one of these kittens, I realize that it must be growing right now, right in front of me. Cells are multiplying, differentiating, turning into organs and limbs and fur, as I watch. You’d think that if I looked hard enough, just as if I were listening intently in a cornfield, I should be able to be able to observe the process happening. And yet all I see is a kitten doing the normal things — eating, breathing, purring — with no detectable sign of the furious activity underneath.

When I was very young, I used to stare at the hour hand on our kitchen clock, trying to catch it in motion. It clearly had to be moving, since it was in a different position each time I returned to the clock, but it frustratingly always appeared to be standing still. My parents’ explanation that its movement was so slow as to be imperceptible by human eyes was something I refused to believe. It was as unappealing as the idea that the earth was too large for me to see its curvature.

We like to think that our senses allow us to see the world as it is, and perhaps they do — but only the small slice of the world that’s available to us. Just as there are entities that are too small or too large for us to see, there are events that are too fast or too slow, wavelengths that are too short or too long. All of these levels of being exist simultaneously, and there’s no reason to believe that our human perception of reality is any better or any “realer” than any of the others. And yet — for me, at least — the only things that feel true are the things I can experience firsthand. All of the rest is just concepts and abstractions.

Clearly I’m not the only one who has this problem. The world, as we now know, is gradually growing warmer, but at a rate that’s too slow for us to experience through our senses. We know that it’s happening, but not in a way that we can perceive directly, and therefore it’s easy and natural for us to dismiss it as not quite real. Just as we can’t see the cells of a kitten multiplying, we can’t see the molecules of carbon dioxide accumulating in the atmosphere. All we can see is what’s on a larger scale — wildfires, droughts, intense weather events — and ask ourselves, as when we see a kitten somehow getting larger: How is this possible?