The Yoga Sutras by Patanjali are aphorisms to help one lead a more joyful life. The one book is divided into four sections, called padas, or books, and short verses called sutras. Pada is Sanskrit for step and Sutra is Sanskrit for stitch or thread. A journey starts with a single step, and new knowledge with a single thread. These sayings that have been written 5,000 years ago are packed with subtle meanings on how to make steps, padas, in the direction of enlightenment. Some scholars say that Patanjali was the same as Charaka who wrote the ancient Ayurvedic texts called the Samhita. In any case, Patanjali took what had been an oral tradition and put the words on paper--or bark as may have been the case at the time.

In the Portion on Practice, Book II, in Sutra 29 the eight limbs of Astanga yoga are outlined: 

 

The yamas, restraints,  are then further described in Sutra 30 as Ahimsa  (non-violence), Satya (non-lying), Asteya (non-stealing), brahmacharya (self-control) and Aparigraha (non-greed). Without these basic foundations in life: peace, truth, trust, self control and contentment we are like paper boats in the ocean blown and tossed this way and that. Each one of these concepts is described in great detail by Patanjali in Book II. 

 

The niyamas are observances and this is the second limb of Astanga yoga before asana, the postures. The observances are Shoucha (cleanliness), Santosha (contentment), Tapah (austerity), Swadhaya (self-study), and Ishwara pranidhana (devotion). Through the practice of abstaining from harmful actions and observing positive ones, we lay the mental foundation for an exploration of yoga.

 

There are several translations of Patanjali's Yoga Sutras. Here are some descriptions of a few of them. Sri Swami Satchidananda gives the Sanskrit sutra in the original devanagari font and in an English pronunciation and translates each word.  This is a good basic text for a beginner.  In the translation by Swami Hariharananda Aranya, more subtle detail is explained, but it may be so deep as to be obscure for some. Another translation by MSI can give you a third viewpoint for understanding the sutras. The translation by Swami Satyananda Saraswati is published by the Biha School of Yoga that has published dozens of scholarly books on yoga and is very clear, although less subtle. The translations by Nischala Joy Devi is written with gender neutral language and has exercises to follow to develop your own practice. B.K.S. Lyengar has a translation with lots of stories that fit his lineages. Baba Hari Das who founded Mount Madonna Institute has translations of Book I and II. Taimni has a translation that is more scientific and Western. There are many more translations, and it's important to find one that appeals to you personally.

 

Even a concept like shoucha, cleanliness, can have many interpretations. Some describe cleanliness as bodily, such as daily routines like tooth brushing, tongue scraping, gargling, cleansing the face, cleansing the eyes, meditation, exercise, bathing, etc. Some scholars see the body itself as unclean and an impediment to liberation since the body can limit us on our path to absolute purity. Finding a translation that speaks to you personally is important in understanding some of these very deep concepts.