When Pococke inquired of Grotius, where the proof was of that story of the pigeon, trained to pick peas from Mahomet's (Muhammad's) ear, and pass for an angel dictating to him? Grotius answered that there was no proof!
Permanence, perseverance and persistence in spite of all obstacles, discouragements, and impossibilities: It is this, that in all things distinguishes the strong soul from the weak.