Today's light · Wednesday 4 November
He moved arithmetic off the dust board and onto paper
In Damascus in 952 a mathematician known as al-Uqlidisi wrote a book on calculating with the Indian numerals. Reckoning was then done on a takht, a board spread with fine dust, where each step was wiped out as the next was written. He argued for ink and paper instead, partly because the dust board was the tool of street fortune tellers and carried their reputation, and partly because on paper the working stays where you can check it. In the same book he uses a mark to separate a whole number from the fraction following it, which is the earliest known use of a decimal fraction. Al-Kashi set decimal fractions out systematically in 1427, and Simon Stevin made them ordinary in Europe in 1585.
Al-Uqlidisi · Damascus, 952 CE
Wednesday 4 November 2026 · 23 Jumada al-Ula 1448 AH
The word · Hadith
المُسْتَدْرَك
Mustadrak
Al-Hakim's supplement, gathering hadiths he judged to meet the standards of al-Bukhari and Muslim.
A mustadrak is a book that makes up what an earlier author left out. Al-Hakim al-Naysaburi compiled his late in life and never finally revised it, and later scholars including al-Dhahabi found him lenient. A grading of sahih from al-Hakim alone is therefore treated as a starting point for checking rather than as a settled verdict.
The Path · chapter 55 of 71
الدجال
Ad-Dajjal: The Great Deceiver
One-eyed. The word kafir written on his forehead. The greatest fitnah until the Hour.
The last trial is epistemological: eyes lie, revelation does not
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