Is it true that mankind today has reached such a level of progress that they have no need of the Messengers and their teachings? Are humans capable today of guiding themselves without referring to the methods set out by the Messengers? The answer is No. Mankind needs to know the Messenger, and the Message he conveyed. They have to believe in what he said and obey him. The only way to achieve happiness and success in this world and in the Hereafter is to follow the Messenger. By following the Messenger, man will become aware of the details of good and evil, and Allah will be pleased with him. His guidance comprises good deeds, good speech, and good morals. His speech and conduct are the criteria against which all actions are measured. Without a Messenger's guidance, man is like a fish out of water. When man abandons this guidance, then his heart is spoiled. Since man's happiness in this world and in the Hereafter is linked to the guidance of the Prophet, one should know well the prophet's teachings and biography in order to join his true and successful followers. This comprehensive work which is full of clear proofs and evidences from the pure teachings of Islam, is an essential reading for all Muslims and seekers of truth.