About Me



Michael Castor is the author of this blog, “Quintessential.

Michael is also the portfolio manager of the healthcare-focused hedge fund, Sio Capital Management, LLC, which he founded in 2006. Before starting Sio, Michael worked at Bernstein Investment Research and Management from 2001 to 2006 as the firm’s healthcare analyst and as the healthcare sector leader. Prior to Bernstein, Michael worked in the investment banking/equity capital markets division of JP Morgan where he focused on biotechnology and healthcare equity offerings.

Before entering finance, Michael spent three years in clinical medicine. He completed his surgery internship at Indiana University Medical Center followed by two years of surgery and otolaryngology residency at Columbia Presbyterian Medical Center in New York. Michael earned his MD degree from The Ohio State University College of Medicine where he graduated summa cum laude. He earned his undergraduate degree in biomedical engineering from Tulane University where he graduated summa cum laude with departmental honors.

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quin·tes·sen·tial   [kwin-tuh-sen-shuhl]
Representing the true nature, embodiment, and essence of a thing

Quintessential, as a word, is elegant in both its meaning and its etymology.  Quintessence derives from Latin (quinta essentia) and translates to “fifth essence.”  In classical times, it was believed that there were four elements: earth, wind, fire and water.  Greek scientists/thinkers held that there was also a fifth element, sometimes referred to as “Aether,”  which represented heaven and the true essence of the Gods.  This element superseded and unified the others.  Plato described Aether as “”that which God used in the delineation of the universe.”

Therefore, along with having rich meaning, the word quintessential captures elements of history and science.  As for this blog, it is my hope that some of my observations will capture the true nature of things.

I learned the etymology of “quintessence” when I read Hamlet.  My copy had footnotes that explained certain anachronistic phrases or significant passages.  There was such a notation next to “quintessence.”  This  footnote detailed the word’s origin.

Hamlet, Act II, scene ii

What a piece of work is a man, how noble in reason, how
infinite in faculties, in form and moving how express and
admirable, in action how like an angel, in apprehension how like
a god! the beauty of the world, the paragon of animals—and yet,
to me, what is this quintessence of dust?

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