Grimm's Law

Most important philological discovery of this century, gue ed in part by Rask, but worked out by Jakob Grimm, and called by him Lautverschiebung, sound-shifting. By this law, certain consonants in Sanskrit, Greek, and Latin (the first stage), are represented by regularly-related sounds in oldest German, Gothic, Anglo-Saxon, etc. (the second stage). 1. The surd explosives p, t, k, of the first stage, become f. th. h, in the second stage; cf. Latin tres with English three. 2. The sounds f, th, h (in oldest forms bh, dh, gh ), of the first stage, become b, d, g, in the second stage: cf. frater with brother. 3. The sonant explosives b, d, g, of the first stage, pa into p, t, k, of the second stage: cf. Latin duo with English two. Certain apparent exceptions have lately been explained as perfectly regular by Verner's Law. There has been a second sound-shifting from the second stage to a third, that of High German. Thus Latin tu, English thou, German du; while English t, p, d often become z (ts), pf, and t, along with other changes.