Nearsighted people experience blurred vision while looking at distant objects, such as street signs viewed from inside a car. Conversely, farsighted people experience blurred vision while looking at nearby objects, such as words on a page. The causes of these two conditions differ as well. Nearsightedness, or myopia, occurs either when a person's eye is too long from back to front or when the cornea (the clear layer at the front of the eye) is too curved. On the other hand, farsightedness, or hyperopia, results when the eye is too short or when the cornea is not curved enough. Fortunately, corrective lenses can restore normal vision in both cases. As you might expect, these lenses are of opposing types: nearsightedness is improved with a lens that is thinner in the middle and thicker at the edges, while farsightedness is compensated for with a lens that is thicker in the middle and thinner at the edges. The main idea of the passage is Nearsightedness and farsightedness produce contrasting vision problems, have opposite causes, and require different types of lenses. How does the detail in bold develop the main idea? It contrasts the cause of farsightedness with that of nearsightedness.

It addresses a common misunderstanding about the causes of farsightedness.

the thousand and one nights – or, as i prefer to call them in the following for purely practical reasons: the arabian nights – as we perceive them three hundred years after antoine galland’s epochal french adaptation bear a distinct arabic imprint. meanwhile, the commonly accepted model for their textual history acknowledges various stages in the conceptualization and effective formation of both the collection’s characteristic frame story and the embedded repertoire. the vast majority of tales in the preserved manuscripts of the nights has been integrated into the collection during two periods of arabic influence, the so-called baghdad and cairo periods (gerhardt 1963: 115–374). these “arabic” stages are preceded by an iranian version, probably dating to pre-islamic times, which in its turn profits from both structural devices and narrative contents originating from indian tradition. considering the eminent position that iran and iranian culture hold in the early stages of the textual history of the arabian nights, surprisingly few details are known concerning the collection’s relation to and its actual position within the iranian cultural context. in the following, i will discuss links between the arabian nights and iranian culture on several levels. in surveying these links, i will treat five major areas: (1) the iranian prototype of the nights; (2) tales of alleged persian origin; (3) persian characters within the tales; (4)persian translations of the arabian nights; and (5) the position of the arabian nights in modern iran