Have you ever wondered why the doctor asks you to stick out your tongue during an office visit? Apparently the tongue tells a lot about our physical health. For instance, a white patchy tongue is suppose to be an indicator of infection in the body. A dark red tongue is said to indicate you are low in B12.
The tongue is not only a frequent theme in Proverbs, it is the subject of many verses in the Bible.
Psalm 34:13 – “Keep thy tongue from evil, and thy lips from speaking guile.”
Proverbs 21:23 – “Whoso keepeth his mouth and his tongue keepeth his soul from troubles.”
James 3:5-6 – “Even so the tongue is a little member, and boasteth great things. Behold, how great a matter a little fire kindleth! 6 And the tongue is a fire, a world of 
iniquity: so is the tongue among our members, that it defileth the whole body, and setteth on fire the course of nature; and it is set on fire of hell.”
In today’s proverb, Solomon returns to the allegory of a tree, one he names the “tree of life”.
Proverbs 15:4 – “A wholesome [healing; curing; soothing] tongue is a tree of life [like medicine to the soul]: but perverseness [crooked; deceiving words] therein is a breach [breaks; destructive] in the spirit.”
Words are powerful. Words have the power to heal and to hurt, to lift a hurting soul or crush the last gasp of hope in a desperate life. Like salve on a wound, words have the power to sooth, encourage and inspire. It has been my observation that few evidence the spirit of an encourager whose words heal, encourage and comfort.
Too many readily join the chorus of naysayers, critics and cynics. Many souls are crushed and spirits quenched by lies, deception and disloyalty (all expressions of “perverseness”). Some reading today’s parable have a way with words that crush the spirit and wounds the soul. Your words and manner have a way of “taking the wind out of another man’s sails.”
Proverbs 18:21 – “Death and life are in the power of the tongue: and they that love it shall eat the fruit thereof.”
Do your words heal and encourage or break the spirit of those you love?
The words that proceed out your mouth are indicative of the spiritual condition of your heart.