Baro, Baru or Baron Urbigerus was a seventeenth-century writer on natural philosophy and alchemy.[1] He is known for his Aphorismi Urbigerani (1690).[2] This collection of 100 aphorisms claims to set out completely the theory of the alchemical work, the preparation of the Philosopher's Stone. A shorter collection of 31 aphorisms, contained in it, is known as the Circulatum Minus Urbigeranum.[3] This work exists in German and English versions.