spoke to truth to power

[Jignesh77]

Kofi Annan spoke to truth to power.
I read this online.
What we can learn from Kofi Annan

What does "spoke to truth to power"?
I don't the grammatical structure of this phrase?
I don't understand the uses of "to" used before "truth" and "power".

 

[entangledbank]

It should be 'spoke truth to power': told the truth to powerful people.

New idea. Or 'spoke the truth to power', and 'to' mistakenly displaced 'the' by anticipation.

 

[kentix]

"Speak/Spoke truth to power" is basically a set phrase in American English.

What Does It Mean To "Speak Truth To Power"?

Bayard Rustin

The specific phrase speak truth to power is credited to Bayard Rustin in 1942. Rustin was a Black Quaker and a leader in the Civil Rights Movement, advocating nonviolent methods in his fight for social justice.

Speaking truth to power - Wikipedia