Satyarth Prakash (The Light of Meaning of the Truth or The Light of Truth) is written by Dayanand Saraswati in 1875.
It is considered one of his major scholarly works.
The book was originally written in Hindi and subsequently revised by Swami Dayanand Saraswati in 1882.
This book is now translated into more than 20 languages including Sanskrit and several foreign languages like English, French, German, Swahili, Arabic and Chinese.
The major portion of the book is dedicated to laying down the reformist advocacy of Swami Dayanand with the last three chapters making a case for the comparative study of different religious faiths.