The Platonic cosmos, object of knowledge, no doubt forms an intelligible and continuous whole, its several levels being linked by carefully calculated means (Tim. 37a). The same, however, cannot everywhere be said of human knowledge. Indeed, the several levels of knowledge as presented for instance in the figure of the divided line, tend to become disassociated,1 despite the apparent analogy which held between these levels. Precisely for this reason skepticism hovers in the background of a Platonic philosophy. Plato, at least in his earlier dialogues, no less than the Christian Platonists recognized this danger and both completed their rational doctrine with another, Plato with a myth and the Christian philosopher with faith. I wish to show just why the Platonic doctrine of knowledge common to both groups of philosophers tends to break and exactly at what point the Christian would rescue it with faith. Thus it will become evident that some such rescue was necessary if Plato was to accept Heraclitus' guide and think the logos of the world to its completion.