"Yoga teaches us to cure what need not be endured and endure what cannot be cured".- Yoga is an art, a science and a philosophy that touches the life of man at every level, bodily, intellectually and spiritually. All yoga as practiced today is based on Yoga Sutras, a collection of aphorisms offered more than 2000 years ago by the Indian sage, Patanjali. Yoga Sutras by Maharshi Patanjali are known as the Patanjali Yoga Sutra and is the foundational text for Yoga. Historically, it is believed that Maharshi Patanjali may have lived in around 500 BC to 2000 BC and Patanjali has written on mainly three subjects namely, grammar, medicine and yoga. Patanjali`s three works together deal with man`s development as a whole in thought, speech and action.
Patanjali Yoga Sutra consists of 196 sutras which are divided into four chapters or padas. Each sutra consists of Sanskrit words that are written in one or two lines. The 196 sutras are precise, reflective and pious in approach. Each of the sutras contains a wealth of ideas and wisdom towards full knowledge of his real nature. The Patanjali yoga sutra state, through proper practice one can radiate grace, disposition and compassion. The four chapters or padas of the yoga sutras correspond to the four stages of life. The ultimate achievement of following the path of Patanjali yoga sutra is to experience the effortless, indivisible state of the prophet. The four chapters of Patanjanli Yoga Sutras include, Samadhi Pada, Sadhana Pada, Vibhuti Pada and Kaivalya Pada.

In this pada, Patanjali comes to the level of those who not spiritually evolved. Here he coins the word KriyaYoga. Kriya means action and KriyaYoga emphasizes the energetic effort to be made by the aspirant. This pada is composed using the eightfold paths of yoga. All the eight disciplines are compressed into three-tier format. The tier formed by the first two pairs, yama and niyama, asana and pranayama, comes under tapas (religious spirit in practice). The second tier, pratyahara and dharana, is self-study (svadhyaya). The third, dhyana and Samadhi, is Isvara pranidhana, the surrender of the individual self to God. In this way, Patanjali covers the tree great paths of Indian philosophy in the Yoga Sutras. In the Sadhana pada the seeker is taught to perform asana (postures) so that he becomes familiar with his body, senses and intelligence. He develops alertness, sensitivity and the power concentration.
Sadhana Pada is the second chapter of Patanjali Yoga Sutra, where Patanjali comes down to the level of those who are not spiritually evolved. Patanjali in this chapter identifies that Avidya or spiritual ignorance as the source of all sorrow and unhappiness. Here he coins the word, Kriya Yoga. Kriya means action and KriyaYoga emphasizes the energetic effort to be made by the aspirant. First, he explains the concept of Kriya Yoga, which is the yoga of action and has three tiers, namely tapas, svadhyaya and Isvarapranidhana. Tapas means burning desire, Savadhyaya means self study and Isvarapranidhana means surrender to God. When these three aspects of kriya yoga are followed earnestly, life`s sufferings overcome and Samadhi is experienced. He also explains causes of sufferings and how to minimise it; followed with the eightfold path of Yoga to achieve freedom for common man. This eight fold path is known as Astanga Yoga which is suitable to all. These eight steps are namely the yama, niyama, asana, pranayama, pratyahara, dharna, dhyana and samadhi.
Yamas are social moral conduct; while Niyamas are to be observed for self-development. Asana is a comfortable, steady and peaceful posture to make the physical body strong and ready for inner journey and Pranayama is the controlling of bio-energy. The first four steps are external supports called Bahiranga and last three are internal aid called Antaranga. Pratyahara is the connection between external and internal. It consists of controlling of five sense organs. In the chapter of Sadhana pada, Patanjali explains the journey from yama to pratyahara.
Vibhuti pada is the next chapter of Patanjali Yoga Sutra. Vibhuti is the Sanskrit word for "power" or "manifestation". This chapter speaks of the divine effects of yoga sadhana. When a sadhaka attains expertise in the steps of the first five steps, he acquires the eight supernatural powers or siddhis. However, Patanjali cautions that the temptation of these powers should be avoided and the attention should be fixed only on liberation. Patanjali then explains Dharana or concentration, Dhyana or meditation, which comes from repeated concentration and Samadhi, which comes from deep absorption.
Kaivalya Pada is the fourth chapter of Patanjali Yoga Sutra. Kaivalya literally means "isolation", but as used in the Sutras depicts the idea of liberation or moksha (liberation), which is the intention of Yoga. The Kaivalya Pada describes the nature of liberation and the reality of the transcendental self. In this chapter, Patanjali distinguishes kaivalya from Samadhi. In Samadhi pada, the aspirant experiences a passive state where he can see his soul and in kaivalya he lives above the tamasic, rajasic and sattvic influences of the three gunas of nature (the primary qualities of Nature). The ultimate aim of Yoga is to achieve Kaivalya that can be achieved by birth, through use of drugs, by repetition of mantra, by tapas and through Samadhi. Of these, only the last two develops to matured intelligence and lead to stable growth.
Patanjali Yoga Sutra explains that the soul is pure and divine provided it is unblemished by action. Man may make or ruin his progress through good actions or bad action. Yogic action leads to religious life and non-yogic actions bind one to the world. With yogic practices the sadhaka is freed from the reactions of his actions and engrossed in Kaivalya. The Patanjali yoga sutra state, through proper practice one can radiate goodwill, friendliness and compassion. The four chapters or padas of the yoga sutras correspond to the four stages of life. The ultimate achievement of following the path of Patanjali yoga sutra is to experience the effortless, indivisible state of the prophet. Patanjali Yoga Sutra stands as the non-theistic doctrine of Yoga Sutra. There is not even the slightest suggestion of worshipping idols, deities, gurus, or sacred books; but at the same time, Patanjali Yoga Sutra does not even contain any atheistic doctrine either. Amidst the four chapters, Patanjali Yoga sutra affirms that yogic practice is the path to experience the ultimate reality. Thus, Patanjali Yoga Sutras is a complete guide or path to achieve Kaivalya whether the sadhaka is spiritually evolved or not.