The author of this treatise is Imam abu Jafar al Tahawi (239 - 321 AH), one of the leading authorities on the Hanafi madhab. The period he lived in was the zenith of the dissemination of the Islamic sciences and Imam at Tahawi was one of the giants this era produced.
To illustrate this; his teachers included Imam Ismail ibn Yahya Al Muzani (a major student of Imam al shaafi), he collected hadith from Imam an-Nasai (author of Sunan an-Nasai, one of the saheeh Sittah) and his students included the great Muhaddith Imam At-Tabarani.
The purpose of this treatise was to state the creed of the early scholars of the Hanafi madhab and to indicate its correlation with the views of Ahl As-Sunnah Wal Jamaah in general. Imam Dhahabi (673-748 AH) said about At-Tahawi - He was the muhaddith and faqih of Egypt, equally distinguished in both fields. Whoever reads the word of this Imam is sure to acknowledge his erudition and width of vision. Ibn Kathir (702-774 AH) said - He was the most reliable and correct narrator of hadith and one of the greatest scholars of hadith. Ibn Hajr Al Asaqalani (773-853 AH) said - He was a reliable narrator, a great scholar, a famous jurist, very knowledgeable concerning the controversies of the jurists, and a man of keen interests.