Today, we are in the park, both dressed in anoraks; Harry's bright red, mine a more sober blue. We were heading for the swings but the deep pile of fallen leaves, baked golden brown by the autumn sun, was too great a treasure to resist. I picked up a handful and threw them towards him and he caught the idea immediately. Now, they are scattered all over the grass and path. He turns back for more ammunition but his attention is snagged by something else.

I step forward quickly to make sure that he has not found something... unpleasant... but it is only a stone. He has closed his chubby fists around it and is tugging but it remains unmoved. Harry ends up on his backside, his fall cushioned by the leaves. His face is such a perfect, almost cartoon-like, mask of surprise that I have to resist the urge to laugh.

The surprise changes to determination and he clambers back to his feet to tackle the stone again. I go through the options. The stone is not very large and I could probably pick it up quite easily, but this is Harry's challenge and he needs to succeed at things for himself. On the other hand, if it proves impossible for him to move, he will get frustrated and the fun of finding whatever is underneath will be quickly lost. I am caught in a balancing act of letting him explore the world for himself and making sure that it does not get the better of him.

He has a firmer grip on the stone now, with both hands at one end and nearer to the ground. Confidently, he tugs at it with all his strength and this time it definitely moves. Slightly. He straightens up and glares at the stone, then turns to me and points at it. His language skills are not yet developed enough for him to express exactly what is on his mind but his expression clearly says, “That bloody rock won't move!”

“Is the rock giving you a hard time, Harry?” I ask, sympathetically.

He nods, the pun entirely lost on him.

“Shall I have a go? My hands are bigger than yours; maybe I can get that silly rock to move.”

He steps back a little and I approach the stone. I make a show of examining it from all angles, then rub my hands together and seize it firmly. Harry is watching every move with critical attention, perhaps comparing my technique to his. The base of the stone is below the soil, which is presumably why Harry could not move it. A quick wiggle from me is enough to loosen it but I do not pick it up.

“I think it's going to take both of us, Harry,” I tell him. “You grab that end, that's it. Now pull!”

The stone comes free and we both fall laughing into the leaves. We have disturbed a community of tiny creatures that hurry away in all directions. They are mostly woodlice but there are also a couple of spiders and an earthworm. Harry gets back to his feet and watches them but makes no attempt to touch them. He is a squeamish toddler and does not like to get too close to things that crawl or wriggle.

Suddenly, the earthworm begins to head for Harry's wellies. Instinctively, he raises one foot and it seems that the worm is about to pay the ultimate price for its attack. I scoop Harry up just in time and he cries out in protest. My explanation that earthworms are helpful creatures falls on deaf ears. He has been denied his chance to slay a monster and I am in the doghouse.

It is going to be a long day.