Shiva invented and systematized Tantra, which is a practical spiritual science that leads to liberation. Proper disciples and preceptors are needed to practice Tantra successfully. There are three types of disciples - those who forget everything when away from the teacher, those who neglect to preserve what they learn, and those who safely keep the teachings in their heart. Similarly, there are three types of preceptors - those who only give speeches, those who ensure disciples follow teachings but are not demanding, and those who ensure disciples diligently practice through pressure if needed. Total surrender of the disciple to the competent preceptor results in spiritual progress through Tantra.