Magnifying glass

A magnifying glass is a double convex lens with a short focal length. When an object is placed under the magnifying glass, an image is produced and also appears larger than the original object.

If you direct the rays of light through the magnifying glass, the rays are bent towards a point on some combustible materials, like papers or dry cloth. Not for long, the dry materials may burst into flames. Yes, if you focus on your business, not for long, you will succeed! However, if you simply focus for to a short while or keep moving your focus point, then success is an illusion.

Similarly, if you boil a kettle of water for a minute or two and turn off the flames and repeating this process many times over, the water in the kettle will remain not boiled forever.