1.10 In deep sleep there is an absence of thoughts.

“Though sleep and meditation may appear the same on the outside, deep, dreamless sleep is heavy and unconscious, while deliberately meditating inwardly is alert and conscious.” –Nicolai Bachman, The Path of the Yoga Sutras

1.11 Memory is thinking about a prior experience.

“Memories create impressions in the mind and at a later time come to the surface, either when we want them or sometimes even when we do not want them.” –Sri Swami Satchidananda, The Yoga Sutras of Patanjali