Classicly

The study of the origin of family names is at the same time quite simple and very difficult. Its simplicity consists in the fact that surnames can only come into existence in certain well-understood ways. Its difficulty is due to the extraordinary perversions which names undergo in common speech, to the orthographic uncertainty of our ancestors, to the frequent coalescence of two or more names of quite different Origin, and to the multitudinous forms which one single name can assume, such forms being due to local pronunciation, accidents of spelling, date of adoption, and many minor causes.

It must always remembered that the majority of our surnames from the various dialects of Middle English, i.e. of a language very different from our own in spelling and sound, full of words that are now obsolete, and of others which have completely changed their form and meaning.