There is perhaps hardly a single uncanonical Christian document that is admittedly and indubitably older than Marcion; so that direct evidence there is naturally none.

But neither is there any direct evidence for the antiquity of man or of the earth.

The geologist judges by the fossils which he finds embedded in the strata as relics of an extinct age; so here, in the Gospel of Marcion, do we find relics which to the initiated eye carry with them their own story.
Nor, on the other hand, can it rightly be argued that because the history of these remains is not wholly to be recovered, therefore no inference from them is possible.

In the earlier stages of a science like palaeontology it might have been argued in just the same way that the difficulties and confusion in the classification invalidated the science along with its one main inference altogether.

Yet we can see that such an argument would have been mistaken.