The term 'Tattva' is derived from the Sanskrit root 'tattvam', which means 'principle' or 'truth'. It refers to the fundamental categories or principles that underlie reality in various Indian philosophical systems.

The concept of Tattvas is most prominently discussed in the Samkhya school of Indian philosophy, which is known for its dualistic metaphysics and its emphasis on the distinction between Purusha (consciousness) and Prakriti (matter).

In the Samkhya system, there are traditionally 25 Tattvas, which include the Purusha, Prakriti, and 23 evolutes of Prakriti, known as the Mahat, Ahamkara, and the five Tanmatras (subtle elements) and their corresponding gross elements.

The primary goal of the Samkhya philosophy is to understand the nature of reality and to explain the relationship between Purusha and Prakriti. It seeks to provide a comprehensive framework for understanding the universe and the human experience.

In the Samkhya system, the ultimate cause of suffering is ignorance of the true nature of reality, which leads to misidentification of the self with the material world. This misidentification results in attachment, desire, and aversion, which are the root causes of suffering.

Prakriti is the material cause of the universe in the Samkhya system. It is the primordial, undifferentiated substance from which all material objects and phenomena arise. Prakriti is composed of three Gunas (qualities): Sattva (purity), Rajas (activity), and Tamas (inertia).

Purusha is the source of consciousness in the Samkhya system. It is the pure, unchanging, and transcendental principle that is distinct from Prakriti. Purusha is the experiencer, the observer, and the witness of the material world.

Purusha and Prakriti are two aspects of the same reality in the Samkhya system. They are not separate entities but rather two complementary principles that interact with each other to create the universe. Purusha is the consciousness principle, while Prakriti is the material principle.

The goal of the Yoga philosophy is to achieve liberation from suffering (duhkha) and to attain a state of spiritual enlightenment (moksha). This is achieved through the practice of yoga, which involves physical postures, breathing exercises, meditation, and self-inquiry.

The eight limbs of Yoga, as described in the Yoga Sutras of Patanjali, are Yama (moral restraints), Niyama (observances), Asana (physical postures), Pranayama (breath control), Pratyahara (withdrawal of the senses), Dharana (concentration), Dhyana (meditation), and Samadhi (enlightenment).

Meditation is a central practice in the Yoga philosophy and is seen as a means to achieve a state of spiritual enlightenment (moksha). Through meditation, the yogi seeks to transcend the limitations of the mind and to experience the true nature of reality.

The Samkhya and Yoga philosophies are two aspects of the same philosophical tradition, known as the Samkhya-Yoga system. While the Samkhya philosophy focuses on the metaphysical principles of reality, the Yoga philosophy focuses on the practical methods for achieving spiritual liberation.

Atman is not a Tattva in the Samkhya system. Atman is a concept in the Vedanta school of Indian philosophy, which refers to the individual self or soul.

Dharma is not one of the three Gunas in the Samkhya system. Dharma is a concept in Indian philosophy that refers to moral duty, righteousness, and ethical conduct.

Atman is not one of the five Tanmatras in the Samkhya system. Atman is a concept in the Vedanta school of Indian philosophy, which refers to the individual self or soul.