Dear @neilhimself: I was so moved by your speech about Terry Pratchett that my wife @swirlgirl31415 & I made these in your and his honor. The bacteria making light use an enzyme called luciferase, which seemed fitting. Great respect and best wishes. (1/3) #LettersOfLivingLight

Dear @neilhimself: I was so moved by your speech about Terry Pratchett that my wife @swirlgirl31415 & I made these in your and his honor. The bacteria making light use an enzyme called luciferase, which seemed fitting. Great respect and best wishes. (2/3) #LettersOfLivingLight

Dear @neilhimself: I was so moved by your speech about Terry Pratchett that my wife @swirlgirl31415 & I made these in your and his honor. The bacteria making light use an enzyme called luciferase, which seemed fitting. Great respect and best wishes. (3/3) #LettersOfLivingLight