Clay alone cannot make a pot. It needs water in the process of creation. When the pot is ready, what does it hold? Water! Thus, a pot that has to hold water cannot be prepared without the use of water.
Similarly, our mind that has to hold God in it needs to be prepared with the help of God. Just like the pot first needs water in its creation, likewise our mind first needs God in order to be made ready. When it is ready, it will accept and retain God just like a pot holds water.