The meaning of the proverb is self-evident. We invent what we need; unless we feel the pressure of needs, we are not likely to invent anything. The fable of the thirsty crow who collected pebbles and threw them into the jar to raise the level of water to the bird's reach of lips is well-known.
During the Great War, the British and French ships carried on blockade of German ports. The supply of sugar, oil and many other essentials stopped, But the German scientists discovered substitutes and synthetic products to tide over the difficulty, due to constraint of circumstances.
Mere necessity would not help us much if we are not moved by thought. Animals have their needs but because they lack the power of thinking and ingenuity, they cannot invent anything. They act on instinct and follow a beaten track. Hence, the correct formula should be necessity is the mother of invention but only when it is supported by the power of thinking.
This, of course, is obvious. When man feels the pinching need of anything, he begins to think how he can satisfy his needs. He then sets his mind to the task of invention. Necessity gives the first impulse; the rest is the work of the intellect.
An illustration or two will make this clear. In primitive times men lived by hunting. It became necessary to shoot and bring down the bird flying or the beast running beyond the reach of man. Hence, the bow and the arrow were invented. Clothes were devised as protection against cold, houses for shelter. Implements were invented for production of food. In this way, various instruments were made to secure a better standard of living.
But man is something more than a mere slave of his needs. He creates new needs not always, because they are necessary but because they are good or beautiful symbols of status. Culinary skill has been invented to please the palate. Ornaments were invented to add to female beauty. Man has spent millions trying to invent guided locomotives to the moon and other planets like Mars, not because there is any crying need for the same, but because it gives the thrill of doing the outwardly impossible.
Man is not only the slave of his needs but their creator as well. He not only seeks to satisfy his necessity but also his desire for beauty, his lust for power. The mere satisfaction of needs can never be the sole motive for exercising man's faculties for inventiveness. The proverb tells us not to be passive in our attitude to life, not to follow the same old habits and ways to life. The world is changing every day, and we must adapt ourselves to the changing needs and keep pace with them. The more we expand our horizon, the greater will be our incentive to invent new machines and gadgets.