TASK DEFINITION: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
PROBLEM: What is needed to prove the theory?, Context: In the early 11th century, the Muslim physicist Ibn al-Haytham (Alhacen or Alhazen) discussed space perception and its epistemological implications in his Book of Optics (1021), he also rejected Aristotle's definition of topos (Physics IV) by way of geometric demonstrations and defined place as a mathematical spatial extension. His experimental proof of the intromission model of vision led to changes in the understanding of the visual perception of space, contrary to the previous emission theory of vision supported by Euclid and Ptolemy. In "tying the visual perception of space to prior bodily experience, Alhacen unequivocally rejected the intuitiveness of spatial perception and, therefore, the autonomy of vision. Without tangible notions of distance and size for correlation, sight can tell us next to nothing about such things."

SOLUTION: vision

PROBLEM: What did Darwin think about Wallace's theory, Context: Darwin was hard at work on his "big book" on Natural Selection, when on 18 June 1858 he received a parcel from Wallace, who stayed on the Maluku Islands (Ternate and Gilolo). It enclosed twenty pages describing an evolutionary mechanism, a response to Darwin's recent encouragement, with a request to send it on to Lyell if Darwin thought it worthwhile. The mechanism was similar to Darwin's own theory. Darwin wrote to Lyell that "your words have come true with a vengeance, ... forestalled" and he would "of course, at once write and offer to send [it] to any journal" that Wallace chose, adding that "all my originality, whatever it may amount to, will be smashed". Lyell and Hooker agreed that a joint publication putting together Wallace's pages with extracts from Darwin's 1844 Essay and his 1857 letter to Gray should be presented at the Linnean Society, and on 1 July 1858, the papers entitled On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection, by Wallace and Darwin respectively, were read out but drew little reaction. While Darwin considered Wallace's idea to be identical to his concept of natural selection, historians have pointed out differences. Darwin described natural selection as being analogous to the artificial selection practised by animal breeders, and emphasised competition between individuals; Wallace drew no comparison to selective breeding, and focused on ecological pressures that kept different varieties adapted to local conditions. Some historians have suggested that Wallace was actually discussing group selection rather than selection acting on individual variation.

SOLUTION: On the Tendency of Species to form Varieties

PROBLEM: When did the popularity of the Athenian serenades begin?, Context: The Heptanesean kantádhes (καντάδες 'serenades'; sing.: καντάδα) became the forerunners of the Greek modern song, influencing its development to a considerable degree. For the first part of the next century, several Greek composers continued to borrow elements from the Heptanesean style. The most successful songs during the period 1870–1930 were the so-called Athenian serenades, and the songs performed on stage (επιθεωρησιακά τραγούδια 'theatrical revue songs') in revue, operettas and nocturnes that were dominating Athens' theater scene.

SOLUTION:
1870