Imitation of Christ

Non possumus nobis ipsis nimis credere, quia sæpe gratia nobis deest, modicum lumen est in nobis, et hoc cito per negligentiam amittimus. Sæpe etiam non advertimus, quod tam cæci intus sumus. Sæpe male agimus, et peius excusamus. Et passione interdum movemur, et zelum putamus. Parva in aliis reprehendimus, et nostra maiora pertransimus. Satis cito persentimus et ponderamus quid ab aliis sustinemus; sed quantum alii de nobis sustinent, non advertimus. Qui bene et recte sua ponderaret, non esset quid de alio graviter iudicaret. 

We cannot place too little confidence in ourselves, because grace and understanding are often lacking to us. Little light is there within us, and what we have we quickly lose by negligence. Oftentimes we perceive not how great is our inward blindness. We often do ill and excuse it worse. Sometimes we are moved by passion and count it zeal; we blame little faults in others and pass over great faults in ourselves. Quickly enough we feel and reckon up what we bear at the hands of others, but we reflect not how much others are bearing from us. He who would weigh well and rightly his own doings would not be the man to judge severely of another.

Imitation of Christ, II, 5:1