Definitions: (1) showing innocent or childlike simplicity; naive; (2) free from reserve, disguise, or equivocation; fair(3) unpretentious, modest

Synonyms: candid, frank, open

Ingenuous implies one who is actuated by candor and love of truth making them willing to speak their minds without reserve; natural implies a spontaneity lacking artificiality or self-consciousness.

Mythological Figure: The god Mercury [also a symbol for eloquent]