Why cannot a human can see things near than 25 cm?

Humans typically struggle to see objects closer than about 25 cm due to the limitations of the eye's lens and the focusing mechanism. The eye has a minimum focal distance, known as the near point, which is the closest point at which objects can be clearly focused on the retina. As objects move closer, the eye's lens cannot accommodate enough to focus the light properly, resulting in blurred vision. This near point can vary with age and individual differences, becoming further away as people get older.