Who's knocking? It's my husband!

Sami is knocking on Layla's door.

Sami came into my office without knocking on the door.

But Peter continued knocking. When they had opened, they saw him, and were amazed.

But Peter continued knocking and when they had opened the door, and saw him, they were astonished.

For everyone who asks receives. He who seeks finds. To him who knocks it will be opened.

For everyone who asks receives. He who seeks finds. To him who knocks it will be opened.

For every one that asketh receiveth and he that seeketh findeth and to him that knocketh it shall be opened.

For every one that asketh receiveth and he that seeketh findeth and to him that knocketh it shall be opened.

Student A police car pulls up in front, and a cop comes to the front door, and knocks, and says he's looking for me.

So to explain that if you've got an elementary particle and you shine a light on it, then the photon of light has momentum, which knocks the particle, so you don't know where it was before you looked at it.

And the poem goes On the idle hill of summer, lazy with the flow of streams, hark I hear a distant drummer, drumming like a sound in dreams, far and near and low and louder on the roads of earth go by, dear to friend and food to powder, soldiers marching, soon to die.

But global health emergencies like the current Ebola epidemic highlight the folly of these fiscal priorities. Though we may not lean too heavily on our health infrastructure typically, its importance becomes all too apparent when disease and death come knocking at our door.