This is what takes place in the average mind. From morning till evening the will is actively working on the lines to which the mind has become accustomed, the lines which the mind has already formed. For example, consider a person who is always thinking of construction, of how to construct a factory or how to build up a certain type of business. During this time he has been forming lines in this area of his mind or mental being. These lines are open to the imagination, and so the mind goes on working along the same lines which his thought has previously been following, even when he is not thinking specially of those subjects. He still follows the same line he has been thinking on. The lines which the will has made in the mind are the directions along which the imagination unconsciously travels. As it is said, "Where your treasure is, there will your heart be also."