Thinking Is the Function of Which Consciousness?

Thinking can be divided into shallow-level thinking and deep-level thinking. Shallow-level thinking is thinking done by the mind consciousness alone, somewhat like a cursory glance at flowers from horseback; deep-level thinking is thinking done jointly by the mind consciousness and the manas, which 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, cannot truly solve problems, and the doubts in one's mind still cannot be resolved.