Mark 10:25

(ubi sup.) Or else, after saying difficult, He then shows that it is impossible, and that not simply, but with a certain vehemence; and he shows this by an example, saying, It is easier for a camel to pass through the eye of a needle, than for a rich man to enter the kingdom of heaven.

(ubi sup.) How then could either in the Gospel, Matthew and Joseph, or in the Old Testament, very many rich persons, enter into the kingdom of God, unless it be that they learned through the inspiration of God either to count their riches as nothing, or to quit them altogether. Or in a higher sense, it is easier for Christ to suffer for those who love Him, than for the lovers of this world to turn to Christ; for under the name of camel, He wished Himself to be understood, because He bore the burden of our weakness; and by the needle, He understands the prickings, that is, the pains of His Passion. By the eye of a needle, therefore, He means the straits of His Passion, by which He, as it were, deigned to mend the torn garments of our nature.

It may be that by camel, we should understand the animal itself, or else that thick cable, which is used for large vessels.