the fifth century, it is not meant that there were absolutely no Christians in the country before that time. Many reasons, on the contrary, would lead us to believe that some progress in the work of evangelization had already been made. For example, we know that before this time Christianity had obtained a footing in Britain, and there is every reason to believe that a constant intercourse was kept up between her and the neighbouring island. Irish ports, too, were often visited by Roman merchants, and some of these were very probably Christians.
Irishmen, again, were great travellers, and occasionally rose to eminence as bishops and presbyters of the Church in different countries. Mansuetus, first bishop of Toul (A.D. 350), is said to have been Irish, and so also was Celestius, who became one of the chief propagators of the Pelagian heresy. We have not, it is true, any historic record of these Christian Irishmen returning to their own country, or keeping up correspondence with their friends at home; but it is not improbable that some of them did so, and thus introduced the religion which they had learned in a foreign land.
Another probable source of Christian instruction was the number of slaves obtained either by purchase or conquest, sometimes from Britain, and sometimes even from Gaul. Patrick himself was a Christian slave in Ireland long before he thought of visiting the country as a missionary.
These conjectures are borne out by the fact that the ancient legends, however inconsistent they may be in other respects, nearly always agree in stating that a Christian Church existed in the country long before the time of Patrick.
Finally, we have Prosper of Aquitaine telling us
