If there is such a thing as an Age of Aquarius, it began in the late 19th and early 20th centuries. This time period saw the birth of our modern model of the physical universe as physicists and mathemeticians looked at the world with new eyes. This time period also saw something of a spiritual revival in the United States and Europe as work in Eastern religions began to make its way into the public consciousness. One of the first missionaries from India came in 1893 to the United States of America to attend, and speak at, the World Parliament of Religions that was taking place in Chicago in that year.
That young man, Swami Vivekananda, electrified his audience. He became something of a spiritual rock star of the era. Swami Vivekananda swayed an entire generation, both in the West and in his home country of India, with his lectures, books, and individual work.
Raja Yoga is one of his most influential works. When I first came across it in my early 20s it was a shock that set me on a path that has lasted my lifetime. It was my first introduction to the philosophy of Vedanta and the practice of meditation, practices that weren't so common in the 1970s as they are now. It helped shaped the basic threads of my philosophy of life more than any other.
The first half of the book is based on a series of lectures that Swami Vivekananda gave on the subject of raja yoga. It contains a great deal of practical information on meditation and psychology from the Vedantic point of view.
The second half of the book is a translation and commentary on Patanjali's Yoga Sutras. The practices espoused in the Yoga Sutras have been accepted by most, if not all, of India's schools of philosophy.
I've now been able to post Raja Yoga to the Shards of Consciousness Basics page. Raja Yoga, as with all of Swami Vivekananda's writing, is in the public domain. It is, however, difficult to find on the internet, except for a text version on Wikipedia. It is this that I have used to create this formatted version of the text. I trust that the book will be as useful to you as it has been to me.