"This," I said to my husband, pointing to the brownie smears¹ on the floor, the blisters² on my hand, and the clocks that read 10 p.m., "is why I did not marry an optimist³."

My brother was visiting us in South Africa from Hong Kong. After the first day, his 10-year-old daughter, Sophia, and my 11-year-old daughter, Lael, had signed onto a business deal.

I should never have left the girls alone in the lounge. Within minutes the conversation had moved from their savings⁴, their investments, and their earnings⁵ to a foolproof plan.

Lael had approached me sweetly in the kitchen: "Sophia thinks we should bake a huge batch⁶ of cookies, sit outside our gate, and sell them to passersby⁷."

I looked at Lael. "I didn't think it would work either," she smiled. Lael went back to consult Sophia. A little while later, she returned with her.

"How about if we move our couches into the garden and invite passersby into our lounge? Then we can serve them cookies and homemade lemonade ," Lael said.

I looked at Lael again. There was no way around this. A business was going to happen, and I could either alleviate⁸ the damage or go down in flames fighting.

"OK," I said. "What if we bake a batch of cookies at your aunt's house and then sell them to her neighbors?" The girls nodded furiously .

"But," I said quickly, "don't worry if it doesn't work – if the cookies fail or the neighbors don't buy." Lael nodded patiently at me. Sophia stared blankly . She had never had a failed business plan, it seems; she had never heard a warning about one. She was the daughter of an optimist.

The next day we baked. Within minutes, we sold all the cookies to the neighbors. When the profits were divided, each girl got 7 rand (about 66 cents).

"I'm used to making a bit more than this," Sophia confided⁹ to her father.

"Then," he announced to all, "I will get you a stand at the farmers' market."

The girls whooped¹⁰. I began to mutter: "Now don't be disappointed if it doesn't work. You can't just show up at the market and get a stall. Not many people buy desserts first thing in the morning. It's forecast to rain, and it will be quiet."

We spent the good part of Friday night baking – brownies, this time. I spent the bad part of Friday night slicing and packaging brownies and cleaning the kitchen.

On Saturday morning, the girls and their dads set off at 6. At 7:30 they returned. It was cold and raining; I knew it would never work.

"Sold out! " my daughter cheered from the car. "We were sold out!"

"How did you even get in in the first place?" I asked.

"Your brother talked and laughed," my husband replied. "The girls talked and smiled, and the next thing we knew, we were in and sold out."

I looked at my husband. There was something wrong with his voice. And he was beaming dangerously.

He had always been a sensible man, a realist. He was the one who had sat me down to listen to Alain de Botton's secular¹¹ sermon on pessimism¹². He was the one who had said the problem with the West is our can-do attitude, and then when we "can't do," we feel let down. He was the one who had agreed with my dad that pessimists¹³ are stable because they are never disappointed.

He wouldn't switch sides now, would he? Surely not. Not over one little paltry¹⁴ optimist's success.

Later, somewhere in the distance, like a tolling¹⁵ bell, I heard his words: "Lael, should we do this every Saturday?"