This manuscript in Ottoman Turkish conveys the meaning in rhymed couplets of the treatise on the fundamentals of Islamic belief by Birgili Mehmet Efendi (also seen as Birgivi Mehmed). At first glance a simple catechism, a companion to Birgili’s longer Tariqat-i Muhammadiyah (The way of Muhammad), the treatise helped lay the foundations for a lasting intellectual movement, which is seen manifested today in Islamic reformism, generally termed salafism, and even in more extremist and violent ideologies. A former Sufi himself, Birgili came to believe that Sufis had strayed far from devotion to the Quʼran and the practice of the Prophet Muhammad. Some scholars regard Birgili as a fanatic in religious matters, while others point to the moderation in his preaching and writing when compared to later activists such as Qadizade Mehmet (died 1635). Birgili’s concentration on fundamentals did in fact give way to the hardened positions among his followers, which influenced the imperial court and even provoked riots in places as far away as Cairo. Birgili was born in the western Anatolian city of Balikesir, where he studied the standard curriculum and became a Sufi. His talents as a preacher were recognized, and he eventually moved to the town of Birgi, where he spent most of the remainder of his life. Popular in his own lifetime, his works were copied and widely distributed. They were among the earliest printed books in the Muslim world. The verse rendition presented here is by an unnamed writer. It is in a clear naskh hand with rubricated headings. The text is contained within a single green border. The work was composed and copied in 1642.