2 definitions
The Filius regius (n.) is the royal son, the reborn king of alchemy hailed as chief of all things under heaven, a natural likeness of Christ that Khunrath thought God wrote into the Book of Nature.
The Filius regius (n.) is alchemy's royal son, no match for Christ: not begotten of the Virgin but of Mother Nature, he is the soul of nature born of the Logos sunk in matter, and his drama rises from below as Christ's descends.