Now put the pen aside out of your five senses and imagine your recent experience of the pen. See it, hear it, touch it, smell it (and now you can taste it all you want) in your mind.
Notice the difference between the sensory experiencing of the pen and the mental experiencing of the pen.
That's the first noticing the difference exercise of the Matrix Routine. If you play with the the Matrix Routine a bit, you will discover this is a very useful difference to notice.
Kevin L. Polk, Ph.D.
Psychological Flexibility Training: http://www.amazon.com/dp/B004M8S4Z4