What Sir Isaac Newton was doing late at night may surprise you. No, no unearthed scandals involving women or drugs, but instead, a shinier vice: gold.

Isaac Newton was a passionate practitioner of alchemy for over three decades, according to Indiana University professor William Newman and a speech he gave recently at the Perimeter Institute for Theoretical Physics.

Newton invented calculus, described the law of universal gravitation and built the first reflecting telescope. Just a few resume highlights for someone considered to be the most influential scientist in history.

That's why alchemy is a strange hobby for someone who clearly mastered the scientific method. Alchemy involves transmuting one element into another. Only not so much focusing on chemical reactions, as invoking spiritual and philosophical approaches.

Alchemy is now considered a pseudo-science. But even during its height, critics such as Chaucer characterized alchemists as charlatans, and it was banned by Pope John XXII and King Henry IV.

But before you think less of Newton, consider that most experimental scientists of the 17th century believed in it too. Professor Newman also counters that alchemists of the time were more similar to chemists than wannabe magicians. They helped create new drugs, brighter pigments and improved booze distillation.

Newton's involvement in alchemy was never fully secret, more like neglected. Only recently have science historians fully analyzed Newton's extensive writings on the subject.