"... Human utterance is an essence which aspireth to exert its influence and needeth moderation."

"... Human utterance is an essence which aspireth to exert its influence and needeth moderation. As to its influence, this is conditional upon refinement, which in turn is dependent upon hearts which are detached and pure. As to its moderation, this hath to be combined with tact and wisdom as prescribed in the Holy Scriptures and Tablets."

-Bahá'u'lláh, Tablets of Bahá’u’lláh Revealed After the Kitáb-i-Aqdas, p. 198