What agency do you think delivered the philosophy of ancient Greece to our current age?
Wikipedia?
Just about all the ancient philosophical texts in existence today had been recovered in the Latin west by the end of the renaissance. They weren't pieced together from the more philosophical sorts of theological texts from late antiquity (I'm thinking of writers like the
Cappadocians here) or from the theological writers (Anselm etc.) from the early high medieval period. Many of these writers used philosophical vocabulary for theological purposes (
ousia, hypastases) but they didn't transmit the ancient philosophical texts themselves.
The appearance of these in the Latin speaking west was the product of a number of schools of translators in Spain, Sicily and in the Greek-speaking Byzantine empire, translating either Arabic translations of the ancient Greek texts, or copies of the Greek texts preserved by the Byzantines. There were even hugely influential Arabic commentaries on some of the texts, such as those by Averroes.
The Roman Catholic Church actually tried to prevent the spread of Aristotle's writings in the early universities, fearing that these pagan works contradicted Christian doctrine. But ironically, this proscription had the opposite of its intended effect, leading to underground popularity for Aristotle at the University of Paris. Soon everyone was reading him, even though they could be excommunicated for doing so. In the 1200's, more than 1500 years after his death, Aristotle had somehow managed to become a stylish Paris intellectual discussed in all the cafes.
https://en.wikipedia.org/wiki/Condemnations_of_1210–1277
Well, if you can't beat him, co-opt him. It was Thomas Aquinas that finally made Aristotle safe for Christianity, reinterpreting all of the central Christian doctrines in Aristotelian terms. And again ironically, Aquinas' synthesis of Christianity and Aristotle, known as 'Thomism', became the official philosophy of the Roman Catholic Church.
https://plato.stanford.edu/entries/medieval-philosophy/
Then in the 14th and especially in the 15th centuries, the rise of the renaissance (especially in Italy) brought with it a new fascination with the literature of antiquity. This was the time when the Muslim Turks were overrunning the last of the Byzantine empire (the surviving East Roman empire) and many Greek scholars fled to Italy with the most precious texts from their libraries. Italian scholars traveled the known world and searched through every library they could find, looking for ancient texts, or at least copies of them. Many of these scholars were looking especially for pagan literature, and much of the surviving scientific literature of antiquity was caught up in the net.
This is where the modern world got Plato's dialogues and the physico-mathematical works of Archimedes. And hundreds of other texts. Pretty much all of the ancient writings known today were known by the end of the renaissance.
These new materials had revolutionary impacts on European intellectual life. For example the recovery of Sextus Empiricus led to a 16th century vogue for Pyrrhonian skepticism, which in turn led to the work of people like Montaigne and Descartes a century or so later. And to some extent, the whole agenda of modern philosophy has been a battle against hydra-headed skeptical nihilism ever since. It's a big part of what created the modern intellectual world.
http://www.f.waseda.jp/sidoli/LE201_05_Renaissance.pdf