Imagine you're finishing up doing some interior redecorating of your living room. You're more or less satisfied, but you can't shake the feeling that that one corner with nothing in it except a small table looks a bit bare. Suddenly, a remedy to this problem comes to mind. You think to yourself, "I know. I'll put a pot plant here!"
You go shopping and get all the necessary supplies: a pot, some soil, some fertiliser, and, of course, the seed or bulb for the plant you want to grow.
You get home and the time comes to plant the plant. You put the pot on the table, then...
...pour the water you're going to give the plant in the pot first. Next, you put in the soil. Finally, you put in the plant.
"Wait," you're thinking. "The water first?"
Yes!
Well, no. Not really. But putting water into a pot before the soil strikes me as pretty much the same thing as putting milk in before the cereal.