I wonder what the "standard" candle was in real life. Was also looking at Bouger's wikipedia page in Photonometry and randomly found that most of his career was spent in mapping and he was coined the "father of naval architecture"

I don't know if there is a default way to classify light. I assume you could do some sort of calculation based on a concentration of gas used in combustion, but even then it wouldn't make sense. It is pretty crazy that there is a way to define a "standard" candle that emits a "standard" amount of light