3:12

a fig tree cannot produce olives, or a grapevine figs, can it?: James continues to use well-known commodities from everyday life to illustrate important lessons. One reference work notes: “Figs, olives and grapes were the three most common agricultural products of the Judean hills, and alongside wheat and barley they would have constituted the most common crops of the Mediterranean region as a whole.” James’ statement here is in agreement with God’s unchangeable law that “trees [yield] fruit . . . according to their kinds.” (Ge 1:11, 12) The point James makes is that the tree or the vine would produce only the fruit that God intended it to produce. So with this illustration, James again emphasizes that misuse of the tongue is contrary to what is natural and fitting.​—Compare Mt 7:16-19 and Media Gallery, “Fig Tree, Grapevine, and Thornbush.”

Neither can salt water produce fresh water: Salt water, such as seawater, is not fit for drinking, and it will not change into clear, drinkable water. One reference work expresses it: “While fresh water added to salt water does not produce fresh water, salt water added to fresh causes the water to be salty. The poison of the tongue is all-pervasive.” When the person who should bring forth wholesome words also persistently produces hurtful words, something is wrong. The person who uses his tongue in that way can do great harm to others. Each of James’ examples on this subject suggests that humans who use cruel speech are acting in a way that is not only unkind but even unnatural​—out of harmony with the intent of their Creator.