A little learning is a dangerous thing
The central meaning of this famous proverb is that it is only a man of poor knowledge who boasts of his learning and its result is harmful. It is said of Newton that shortly before his death he remarked that he was like a child gathering pebbles on the seashore, while the vast ocean of truth lay unexplored before him. And this is from the mouth of one of the greatest scientists of all times. But it is just like what a really learned man feels. In fact, the more his knowledge increases, the more does he feel how little this knowledge is in comparison with what remains to be known. Only a man of little learning boasts of his knowledge. The harm that this does is incalculable. We all know what great harm a quack does to his patient. His treatment generally results in making the case worse if not in death. A half-trained electrician or mechanic may cause great damage to the machines he handles and may even lose his own life. Naturally, their knowledge is limited, but they think that they know enough. Thus the effect of inadequate knowledge is disastrous.