If you were looking for a needle in a haystack, how would you make that job easier? Would you remove some of the hay or would you add to it? Of course, you would take some away. The more you take away the better the chance of finding the needle.
Now, what if your job was to find needles in haystacks? And, what if I told you the more hay you had the more needles you would find? Well, then, you might opt to add more hay. In fact, if you believed that finding those needles was a life-or-death matter, you might be inclined to add as much hay as you possibly could to increase the chance that more than one needle might be there.
Finally, what if I told you that, really, your job was not to necessarily find the needles? It was only to plant the seed of possibility that the needle might be there simply because it has been proven that a needle exists anywhere a big pile of hay does? All you have to do is collect as much hay as possible so that, should a needle be suspected, there is sufficient hay to back it up.
Now, if you watch the video on this page, at the 7:30 mark, this guy will tell you why the size of the haystack does not matter, what matters is that there is enough hay to prove a needle exists.