Tawheed is the most important of all Islaamic sciences because mastering it means perfecting the necessary basic Islaamic knowledge upon which the reward for good deeds depends, i.e. if Tawheed is not correct one's good deeds will be null and void. This is why Muhammad ibn 'Abdul Wahhad called Tawheed "The head and crux of all religion."
In this book which is translated by Dr. Faruqi the three principles of Tawheed are well-explained. The first principle is knowing Allaah Ta'aala, His Supreme Names and Qualities in the way Allaah Ta'aala explained them in the Qur'aan and as the Messenger Muhammad(Sallallaahu 'Alayhi wa Sallam) taught us in his Sunnah. Besides, the second principle is knowing the Messenger, his sayings, acts, approvals and personal qualities to take him as the most ideal Muslim to be followed by all the Muslims. Then the principle of knowing Islaam, the religion has been dealt with in a scholarly way because knowing the religion should come before acting according to it.
This book as such is a valuable approach to mastering these principles, which no Muslim can dispense with.