KENA UPANISHAD 4:5 [movement of the mind]

Then in that which is the self, there is this movement of the mind, resulting in its thinking, remembering its perpetual intention.

atha adhyatmam yadetat gacchativa cha manah anena chaitad upasmaraty abheekshnam sankalpah

  

Note: this sloka is tied intimately to the previous one. The movement in the mind originates in the lightning of That resulting in the remembrance of what it is.