On this day in 325, the first Ecumenical Council of the Christian Church is held in the city of Nicea, located in modern day Turkey. Today, this Council is commonly referred to as the First Council of Nicea. Among the many decisions made during this meeting were the settlement of the issue of the nature of Jesus and his relationship to God, settling the date for Easter, and issuing a decree forbidding dudes from cutting off their own dicks. I shit you not.
On this day in 1908, Congress ignores the constitutionally mandated tradition of keeping church and state separate by enacting legislation declaring that the motto "in God we trust" should be included on most legal tender.
On this day in 1875, the Metre Convention is signed by 17 nations, leading to the establishment of the "International System of Units". Today, the only industrialized country that does not use the metric system as its official system of measurement is the USA, with the UK also lagging in the adoption of some elements.
On this day in 1980, the people of the French Canadian province of Quebec head to the ballot box to vote on a proposal to begin the work of loosening the bonds of unity with the rest of Canada. The referendum measure receives a 60% NO vote.
On this day in 1983, the journal Science first publishes researcher Luc Montagnier's theory that the HIV virus causes AIDS. Okay, sure, fine, but what is it, exactly, that caused the HIV virus? That isn't as settled a question as most people would like to think. And anyway, if it turns out that HIV wasn't man-made, that doesn't mean the AIDS epidemic wasn't.