If the Light of Truth (Sat) is an Eternal Light, then it can never be overcome by darkness. Any kind of "not-seeing" of the Light is only a belief maintained through and by ignorance.
Therefore the Guru does not remove the darkness to reveal the Light (for the light is Ever-Revealed, Never-Concealed).
The Guru only removes this belief of there ever being something able to cover the Eternal Light.
The Guru removes ignorance, the only darkness there is, and it is an illusory one.
Jai Guru Dev!
Don't fight the mind.
You will never win the mind.
The one who is fighting with the mind
is itself of the mind.
Drop the mind.
realise you have always been
free of the mind,
for the mind appears in you.