The Book in hand is the compilation of the series of lectures that were delivered to a select group of young men over a long period of time by Professor Mohsin Qara'ati. The series of lectures contained in this book have been based on Qur'anic verses and the sayings of the Holy Prophet and his Chosen descendants (peace be on them) with logical conclusions and connotations of the subject-matter being dealt with therein. Unfamiliar terms and unnecessary details have been avoided. Another noteworthy point worth-mentioning is that these lessons were primarily addressed to and meant for the pupils who were about 18 years of age. Besides, the problems that have been discussed in these lessons were solved by citing examples and quoting proverbs. Hence, the problems appear to be interesting and the solution obtained by logic and reasoning are easily understood. In conclusion, this book deals with all the vital problems that confront our younger generation. We hope that this comprehensive book will also help those who are engaged in teaching and learning the principles of Islam. We pray to Almighty Allah to grant us enough strength to acquaint the people in large numbers with the teachings of Islam.This book is one of the many Islamic publications distributed by Ahlulbayt Organization throughout the world in different languages with the aim of conveying the message of Islam to the people of the world. Ahlulbayt Organization (www.shia.es) is a registered Organization that operates and is sustained through collaborative efforts of volunteers in many countries around the world, and it welcomes your involvement and support. Its objectives are numerous, yet its main goal is to spread the truth about the Islamic faith in general and the Shia School of Thought in particular due to the latter being misrepresented, misunderstood and its tenets often assaulted by many ignorant folks, Muslims and non-Muslims. Organization's purpose is to facilitate the dissemination of knowledge through a global medium, the Internet, to locations where such resources are not commonly or easily accessible or are resented, resisted and fought! In addition, For a complete list of our published books please refer to our website (www.shia.es) or send us an email to info@shia.es