The poem talks about “machine” and “engine”. We all know that engine is inside a machine and it is the\xa0driving force\xa0of a machine. The engine also needs fuel to work. When the poet looks at the tree in the beginning , it is silent and still. When the\xa0goldfinch\xa0enters its thickness, a machine\xa0starts\xa0up. The tree is compared to a machine which\xa0starts\xa0working when the engine is filled with fuel. The following lines makes this\xa0clear. “It is the engine of her family. She stokes it full”. Engine refers to the chicks int nest. When\xa0goldfinch\xa0feeds them(fuel), the engine\xa0startsworking and naturally the machine too. So, tree is the machine. Inside it the\xa0baby\xa0chicks in the nest, the engine and the food for them is the fuel.