Yoruba Cosmology resembles a generative system at the foundation of concepts. The traditional thought, which derives from the reality of the identical pair incorporated from cosmology into real life, exemplifies all kind of existing knowledge, culture and practices. Previous studies by the author show in some detail the scientific interests in Yoruba cosmology. The present paper aims to view formal mathematics through the interpretation of Yoruba sky knowledge. It attempts to demonstrate that linguistic codes elaborated from the Yoruba conception of the sky are binary and hexadecimal codes that imply Algebraic Boolean structure or Group Structure. The system is in accord with classical mathematical properties of Group Structure. Finally, the review and interpretation of Yoruba cosmology may suggest the possibility of formal reasoning without any writing system in human history. The problem that has always been raised is that of knowing if symbols and configurations in the Yoruba interpretation of the sky are the result of implicit premeditated mathematical development. It is clear that behind the implicit oral discourse described hereafter lies a corresponding semiology elaborated with the corresponding formal mathematical reasoning that we claim.