Thinking Is the Function of Which Consciousness?

Thinking is divided into shallow thinking and deep thinking. Shallow thinking is thinking done by the mind consciousness alone, somewhat like a cursory glance at flowers while passing on horseback; deep thinking is thinking done jointly by the mind consciousness and the manas, and this requires meditative concentration (samādhi). When the power of concentration is insufficient, thinking remains only on the surface of the mind consciousness and cannot penetrate to the manas; consequently, one cannot truly think things through clearly, cannot truly resolve problems, and the doubts in one's mind still cannot be resolved.