The larger the viewing angle, the larger the image, and the more you can distinguish the details of the object. Moving closer to an object increases the angle of view, but is limited by the eye's ability to focus. Use a magnifying glass so that it is close to the eye and place the object within its focal point to form an upright virtual image. The role of the magnifying glass is to magnify the viewing angle. Historically, it is said that the application of magnifying glasses was proposed by a bishop of England, Grosstheist, in the 13th century.
More than a thousand years ago, transparent crystals or transparent gemstones were ground into "lenses" that magnified images. Also known as a convex lens.