In medieval Europe the numerals we use today weren’t so much unknown as they were taboo. They were sinful, evil, because Christianity.
Numbers were dangerous; at least these Indian [also known as Arabic] numbers were. They were contraband. The zero was the most unholy: a symbol for nothingness, a Hindu concept, influenced by Buddhism and transplanted to Christian Europe. It became a secret sign, a signal between fellow travelers. Sunyata was a well-established Buddhist practice of emptying the mind of all impressions, dating as far back as about 300 B.C. The Sanskirt term for zero was sunya, meaning ‘empty’ or ‘blank.’ Flashing a zero to another merchant let him know that you were a user of Hindu-Arabic numerals. In many principalities, Arabic numerals were banned from official documents. Math was sometimes exported to the West by ‘bootleggers’ in Hindu-Arabic numerals. There is plentiful evidence of such illicit number use in thirteenth-century archives in Italy, where merchants used Gwalior numbers as a secret code.
Hindu-Arabic numerals were so much easier to use in calculations than Roman numerals that they were even considered magical — which, of course, made them more verboten.
I wonder how many mathematicians were burned at the stake.
Lost Discoveries: the ancient roots of modern science — from the Babylonians to the Maya
by Dick Teresi
2002. Simon & Schuster, New York, NY