It has been proved by intelligence tests that intelligence increases and develops when a child grows physically or in age. Mental development takes place differently in different people. The time at which mental progress stops, is not similar in different individuals. It becomes stable after the age of 10 and is fully stabilized during puberty. Intelligence does not grow throughout one's life and it is almost true. The development of intelligence goes in parallel with the development or decline of the nervous system because intelligence is a function of neurons and neuralgia.