Editing Instrumental case (section)

====Old English====
The instrumental case is found in certain usages in [[Old English]]. It has left a legacy in Modern English, in the words "why" and "thus": 'why' is from '''hwy''', the instrumental case of 'hwa / hwæt' (who / what) and 'thus' apparently from '''þys''', the instrumental case of 'þes / þis' (this).

Adjectives and the demonstrative and interrogative pronouns all have instrumental forms. Adverbs are commonly formed in Old English by adding ''-e'' to the adjective, which is the adjective's instrumental case.<ref name=sweet/>

In Old English, the instrumental case denotes means or manner, in such phrases as "'''oþre  naman''' Iulius" ('by other name called Julius') or expressions of time: "'''þy ilcan dæge'''"; 'on the same day'.<ref name=sweet>'Sweet's Anglo-Saxon Primer' (9th edition) (Clarendon Press, Oxford)</ref> (In these examples, the whole expression is in the instrumental case, but only the ''oþre'' or ''þy'' is distinctive in form from the dative.)