Note that he lived 99 years. At the late age of 79, already an esteemed scholar of the Mantrayana at the great Buddhist university of Nalanda, he undertook the difficult overland journey to China in order to transmit the esoteric doctrines and practices. Along with his contemporaries Vajrabodhi and Amoghavajra, Subhakarasimha was responsible for Japan's Mikkyo tradition of the Shingon and Tendai schools. Most famously, he translated the Mahavairocana Sutra into Chinese, wrote a commentary on it, taught the Taizokai Mandala rite, and detailed all the iconography of that mandala. But also, Subhakarasimha was the author of a manual titled "Essentials of Meditation." In it we find his answer to the question:
"SHOULD ONE ATTEMPT TO REMOVE ALL THOUGHTS DURING MEDITATION?"
"O beginners, many of you fear that thoughts arising in your mind will tempt you, and so you follow your breath and maintain a state of no-thought, thinking that this is the ultimate. You seek to improve in this way but cannot.
Thought is of two kinds. One is negative and the other positive. Negative, deluded thoughts should be removed completely. Correct thoughts of the good Dharma should not be extinguished.
Do not be afraid of your mind's workings. Consider it a disturbance of your practice only if you slacken in moving forward . . ." (quoted in "Shingon," p102-3)