Focuses on a Muslim legal science known in Arabic as usul al-fiqh. Whereas the kindred science of fiqh is concerned with the articulation of actual rules of law, this science attempts to elaborate the theoretical and methodological foundations of the law. It outlines the features of Muslim juristic thought.

In "Islam, Spirit, and Form" by Shaykh Osman Nuri Topbas, a profound exploration unfolds, delving into the essence of Islam beyond mere ritualistic practice. In an era where the mechanical repetition of religious customs often overshadows the true spirit of Islam, this book serves as a beacon, aiming to reignite the spiritual radiance inherent in Islamic worship. With a unique blend of historical narratives, tales of prophets and their companions, and the lives of exemplary Sufis, Shaykh Osman Nuri Topbas weaves a tapestry that seeks to illuminate the profound connection between the spiritual essence of Islamic practice and its ritual form. Drawing inspiration from the poetry of Rumi, Yunus Emre, and other Sufi luminaries, the author endeavors to infuse passion into the spiritual journey. The book meticulously dissects the Five Pillars of Islam, offering insights into faith, belief in angels, books of Allah, prophets, the Hereafter, and destiny. The author provides an eloquent exploration of prayer (Salat/Namaz), unraveling its prerequisites, its significance in congregation, and its role as a unique refuge in the journey toward spiritual fulfillment. The chapters on Zakat and Infaq (Poor-Due and Spending for Others) not only elucidate the economic philosophy integral to Islam but also exude a captivating beauty in their exploration of the etiquette of spending and the requirements of Zakat. As the narrative unfolds to the pilgrimage to Mecca and the holy month of Ramadan, Shaykh Osman Nuri Topbas provides rich insights into the construction of the Ka'aba, the significance of the Lesser Pilgrimage (Umrah), and the profound spiritual journey of fasting during Ramadan. "Islam, Spirit, and Form" is not just a book; it is a guide that invites readers to rediscover the profound spiritual dimensions of Islamic practice. Shaykh Osman Nuri Topbas navigates the intersection of faith and ritual, providing a compelling roadmap for those seeking to imbue their religious journey with genuine spiritual essence.

In 1932, the eminent British scholar of Islam, Sir Hamilton Gibb, wrote: "The nobility and broad tolerance of this religion [Islam], which accepted all the real religions of the world as God-inspired, will always be a glorious heritage for mankind. No other society has such a record of success in uniting, in an equality of status, of opportunity, and of endeavor, so many and so various races of humanity." (Whither Islam?) Such scholarly objectivity towards the tolerance which has historically characterized the Islamic tradition as a whole is in short supply these days. Through an insidious symbiosis of fanatical Muslims and prejudiced Islamophobes, the very opposite image of Islam has emerged as one of the most dangerous stereotypes of our times. The most cursory glance at history will not only reveal the falsity of this stereotype of an intolerant Islam, it will also reveal the little known fact that, not so long ago, it was the Islamic world that provided models of tolerant conduct for a fanatically intolerant Christian world tearing itself apart over dogmatic differences. The first part of this monograph examines the historical record of tolerance in the Islamic tradition, illustrating the expression of the principle of tolerance through the rule of such dynasties as the Ottomans, Mughals, Fatimids, and the Umayyads of Spain. In the second, the principle of tolerance is shown to be rooted in the spirit of the Qur'anic revelation and embodied in the exemplary conduct of the Prophet.