Kalama Sutra

Do not accept anything on (mere) hearsay.
Do not accept anything by mere tradition.
Do not accept anything on account of mere rumors.
Do not accept anything just because it accords with your scriptures.
Do not accept anything by mere supposition.
Do not accept anything by mere inherence.
Do not accept anything by merely considering the reasons.
Do not accept anything merely because it agrees with your pre-conceived notions.
Do not accept anything merely because it seems acceptable.
Do not accept anything thinking that the ascetic is respected by us.
But when you know for yourselves -- these things are immoral, these things are blameworthy, these things are censured by the wise, these things, when performed and undertaken conduce to min and sorrow -- then indeed do you reject them.
When you know for yourselves -- these things are moral, these things are blameless, these things are praised by the wise, these things, when performed and undertaken, conduce to well-being and happiness -- then do you live acting accordingly.

The Buddha

The words of wisdom above spreaded through the generations, for the gem of truth is the only permanent entity in the nature.