Attention has a natural habit of becoming attached to thoughts that are being thought. Normally the attention tends to easily get caught up in your thinking because that is the most active part of you, the part that is activated the most easily, and that attracts the attention most easily. The attention also tends to become attached to a train of thought and keep going from one thought to the next that is somehow associated with it, so that it is difficult to stop thinking and experience just the stillness of the soul.