Wonder is not childish. It is the natural state of a mind that has not forgotten how to see.

Children are extraordinary at wonder. A snail crossing a path. A thunderstorm. The way their own fingers move when they concentrate on them. The night sky. Shadows. Their own reflection. Everything, to a child who has not yet been taught what is interesting and what is not, is potentially extraordinary.
Something happens as we grow. The world gets categorized. Familiar. Explained. The snail becomes 'just a snail.' The thunderstorm becomes 'weather.' The night sky becomes background. The capacity for wonder — for genuine, open, amazed encounter with the fact of existence — atrophies from disuse.
This atrophy is not trivial. Wonder is not a luxury emotion for people with too much time. It is one of the most fundamental markers of genuine aliveness — the direct, unmediated encounter with reality that precedes all interpretation. And its cultivation is one of the most reliable paths to the quality of presence that all contemplative practice is ultimately pointing at.
The world will never lack for wonder. Only for those willing to be still enough to receive it.
Albert Einstein — not typically listed among contemplative teachers — described wonder as the source of all genuine science and all genuine art. He called it 'the holy curiosity' and worried deeply about educational systems that killed it in children. He understood, from a secular direction, what the mystics understood from the other side: that the capacity to be genuinely astonished by the fact of existence is close to the source of the deepest human knowing.
In Zen, this quality is called 'beginner's mind' — shoshin. The mind that meets each moment as though for the first time, without the overlay of familiarity, without the dulling effect of 'I already know what this is.' Shunryu Suzuki said: 'In the beginner's mind there are many possibilities, but in the expert's mind there are few.'
Go outside — or simply look out the window — and choose one thing. One ordinary thing. A tree. A cloud. A bird. Your own hand. And look at it as though you have never seen it before. As though you arrived on this planet five minutes ago and this is the first time you have encountered this particular phenomenon.
What is this thing, really? Not what is it called or what is it for. What is it? How did it come to be here? How extraordinary is it that it exists at all — that anything exists at all — rather than nothing?
Stay with this for two minutes. Just two minutes of genuine, open, curious attention to one ordinary thing. And notice what happens to your state of mind. The tightness that was there before may still be there. But something else is also there — a quality of openness, of aliveness, of being genuinely present for the extraordinary ordinariness of being alive on this particular planet on this particular day.
That quality is always available. You just have to remember to look.