{ Say, "Observe what is in the heavens and earth." But of no avail will be signs or warners to a people who do not believe }
The Qur'an is a book that addresses the minds and the eyes so that their faith is based on reflection.
Once Allah orders his slaves to look at the visual signs :
YUNUS (101)
In another verse Allah commands his slaves to reflect on the meanings …
{ Say, "I only advise you of one [thing] - that you stand for Allah, [seeking truth] in pairs and individually, }
SABA (46)
In a third verse Allah asked a question to prove his oneness
{ Do they not see the birds controlled in the atmosphere of the sky? None holds them up except Allah . Indeed in that are signs for a people who believe.}
AN-NAHL (79)