Thirumoolar is one of the most venerated Siddhars in the Tamil spiritual and philosophical tradition. He is considered the author of the "Tirumandiram," one of the most important texts in the Siddha and Tamil spiritual tradition.

Thirumoolar is said to have lived many centuries ago, and is believed to have attained the highest levels of spiritual realization and enlightenment. His teachings are revered for their depth and clarity in explaining the spiritual path to liberation.

The "Tirumandiram" consists of more than 3,000 verses, and is often referred to as the "bible" of Siddha Yoga. It outlines various aspects of spiritual practices, including meditation, devotion, physical health, alchemy, and the nature of the soul.

Thirumoolar emphasized the importance of a pure and disciplined life in order to achieve spiritual growth. He was a strong proponent of yoga, meditation, and self-realization as the means to attain liberation (moksha).

As a Siddhar, Thirumoolar is said to have also practiced the art of healing and alchemy. He was deeply knowledgeable in the medicinal properties of herbs, and is believed to have imparted wisdom regarding the use of herbal remedies for curing diseases.

Thirumoolar’s teachings are particularly noted for their focus on the unity of the individual soul with the supreme, divine consciousness. He stressed that true knowledge lies in the realization of oneness with the Divine and the importance of inner silence and stillness for spiritual awakening.

Today, Thirumoolar's teachings continue to inspire millions of spiritual seekers, and his "Tirumandiram" remains a central text in both Siddha and Hindu spiritual circles.