cast (some) light on (something)
To reveal information or details about something; to clarify or help people understand something. We've hired a private investigator to help cast light on the clandestine dealings of the baron. These documents we've uncovered cast some light on how the late author's final book was meant to end.
cast/shed/throw (new) ˈlight on something
make a problem, etc. easier to understand: This book sheds new light on the role of the CIA.‘Can you throw any light on the matter?’