 Thanks to this first set of translations, learned Muslims became acquainted with Plato’s Demiurge and immortal soul; with Aristotle’s search for science and knowledge of the causes of all the phenomena on earth and in the heavens, culminating in the doctrine of the Unmoved Mover; with Alexander’s cosmology and explanation of providence; with Plotinus’ hierarchy of the principles One, Intellect and Soul; with Proclus’ systematic account of how the One—indisputably identified with Aristotle’s Unmoved Mover—gives rise to the multiplicity of our universe; finally, with John Philoponus’ philosophical arguments for creation. The translation of Proclus’ arguments in favour of the eternity of the cosmos against the Christians, as well as of John Philoponus’ reply to them, also made learned Muslims acquainted with the fact that the Greek philosophers were at odds on some crucial issues. The adaptations which appear in the reworking both of Plotinus’ Enneads (D’Ancona 2006) and of Hyppolitus doxography attributed to Ammonius (Rudolph 1998) show the strategy to deal with this problem typical of the circle of al-Kindi: a strategy which would be successful in the long run. The idea of the basic unity of the Greek philosophical tradition and the twin claim of its intrinsic harmony with the Qur’anic doctrine of the tawhid (divine oneness) will be established by the endorsment, apparent in Kindi’s own works, of the Aristotelian model of the accumulation of knowledge by trial and error (Metaphysics, A and alpha elatton).