At my university there is a weekly thing, where architects from all around the world come to tell us about their ways for two or three hours.
The last one this semester spoke of 'gifts'.
The thing is: no matter how thorough you plan a project of whatever profession, there is always an aspect you forget. He showed pictures of a pavillon made of wood and glass and the gift there was the way the light scattered through the glass in a corner in the very back of the building. Nobody involved with the construction of the pavillon ever thought about how these aspects of the building would interact with another, also with the light coming from outside on the site. How could they? It's impossible to simulate.
This little heart shape on the concrete rubber glove puppet is it's gift. I didn't think of where the air would go when the concrete densed down. But as always it went up and formed a bubble.