It’s devilishly simple.

There’s this curious substance known as Luciferin.  This stuff has the ability to mix with cellular energy – Adenosine Triphosphate or ATP – to create Luciferyl Adenylate and Pyrophosphate.  Got that?  But wait, there’s more.  The Luciferyl Adenylate turns right around and reacts with Oxygen to create Oxyluciferin and Adenosine Monophosphate.  Okay?  But here’s the really wicked part: that second reaction is what your chemistry teacher would have called “exothermic.”  It’s a reaction that gives off energy, in this case in the form of light.  In wavelengths of between 501 and 670 nanometers.  Which the human eye sees as colors ranging from pale yellow to reddish green.  Oh the chemical irony!  Luciferin, named for the Lord of Darkness, can be used to create…a celestial glow!!

And where does this minor miracle happen?  Right in your yard, of course.  Or, more specifically, in the abdomen of an insect your biology teacher would have called Pyrophorus noctiluca.  This little fella flies around with a belly full of Luciferin.  Each time he takes a breath, some Oxygen reaches the Luciferin and produces a short, unmistakable burst of heavenly light.  Then, as he breathes out, the light goes out.  And so on…

You can see it for yourself, in your own homemade biochem lab.  Just go outside this weekend and catch a firefly on your hand.  He will invariably climb up onto the highest point.  And then, before he takes off, he’ll just sit there, getting ready.

Breathing in, and out.  Blinking on, and off.  In, out, on, off.

It’s simple.  It’s miraculous.  It’s wicked.