The research observes thinking processes of students undergoing training to become teachers. It focused on their interpretations which provide a new approach to the ancient text “The Allegory of the Cave” in Plato’s Politeia (The Republic). These processes enable students to reach insights concerning the characteristics of the educator’s challenges of the 21st century. This article is based on a thorough observation of discussions in an online forum (in a Moodle environment), accompanied a lesson entitled “Introduction to philosophy of education on the timeline” that took place during the academic years 2014, 2015, 2016. In this assay we demonstrate how a discussion mediated through an online discourse explores the process of knowledge construction, collaborative learning and constructivist dialog. This is with reference to the tension between the ancient and the modern, the past and the future, tension which its intensity increases in reality changes in accelerated pace.