The Sāṅkhya of the Bhāgavata purāṇa and Sāṅkhya kārikā both agree that the mind is a product of sattva guṇa. Yet, Kṛṣṇa calls the mind caṅcala- flickering in the Bhagavad-Gītā. This is also common experience- that the mind is exceptionally unstable, particularly when one wants to sit down and meditate or chant mantras peacefully. Why is the mind so unstable?
Śrī Babaji’s answer to this question is paraphrased below.
The mind’s nature can be understood by analogy. The mind is like a calm lake. It is in sattva, meaning it is intrinsically peaceful and free of disturbance. But when the wind blows, the waters of the lake are disturbed. Similarly the mind keeps getting influences from the outside through the senses and keeps getting disturbed.
Generally people tend to not do sāttvic activities. Food, actions, association etc. tend to be rājasic or tāmasic. Whatever people consume through their eyes or ears is rājasic or tāmasic. The mind is the first place where all these inputs go. Therefore, the mind remains continually disturbed.
If the mind is to be made peaceful, the winds of rājasic and tāmasic inputs need to be stopped. If one keeps performing rājasic or tāmasic actions, one cannot get peace.
Another consideration is that the guṇas are always mixed. For example, sattva is never pure but is mixed with rajas and tamas, and likewise with rajas and tamas. These guṇas keep changing with time. Even though the mind is a product of sattva, rajas and tamas can also dominate at different times. It is also not necessary that just because the mind is a product of sattva, it must be in sattva.
Similarly, buddhi or intelligence is called superior to the manas or mind in the Gītā, and yet according to Sāṅkhya of the Bhāgavata purāṇa, the buddhi is a product of rajas. [The buddhi is a product of sattva in the Sāṅkhya kārikā]. How can this be understood? The idea is that buddhi is the controller of the mind, and controlling is a function of rajas. Sattva cannot control as it is by nature peaceful and inactive. As such, buddhi is necessarily in rajas.