Words that now have an -igh, like light and high, descend from two groups of Middle English words, distinguished by the length of the vowel. The chart below separates the original two groups by row:

The voiceless palatal fricative [ç], which can be heard in German ich, is made by raising the middle of the tongue to the hard palate. It is distinct from the voiceless velar fricative [x], as heard in the Scots dialect pronunciation of loch; [x] is sounded farther back in the throat.

In these examples, when the [ç] was lost, the preceding vowel, if short, was lengthened.