This brings us back to our unanswered question:  How is it that both English and German developed the curious alternation of unmodified vowel in the singular (foot, Fuss) and modified vowel in the plural (feet, Fuesse)?  Was the pre-Anglo-Saxon alternation of fot and foeti an absolutely mechanical matter, without other than incidental morphological interest?  It is always so represented, and, indeed, all the external facts support such a view.  The change from o to oe, later e, is by no means peculiar to the plural.  It is found also in the dative singular (fet), for it too goes back to an older foti.  Moreover, fet of the plural applies only to the nominative and accusative; the genitive has fota, the dative fotum.  Only centuries later was the alternation of o and e reinterpreted as a means of distinguishing number; o was generalized for the singular, e for the plural.  Only when this reassortment of forms took place[161] was the modern symbolic value of the foot:  feet alternation clearly established.  Again, we must not forget that o was modified to oe (e) in all manner of other grammatical and derivative formations.  Thus, a pre-Anglo-Saxon hohan (later hon) “to hang” corresponded to a hoehith, hehith (later hehth) “hangs”; to dom “doom,” blod “blood,” and fod “food” corresponded the verbal derivatives doemian (later deman) “to deem,” bloedian (later bledan) “to bleed,” and foedian (later fedan) “to feed.”  All this seems to point to the purely mechanical nature of the modification of o to oe to e.  So many unrelated functions were ultimately served by the vocalic change that we cannot believe that it was motivated by any one of them.

[Footnote 161:  A type of adjustment generally referred to as “analogical leveling.”]

The German facts are entirely analogous.  Only later in the history of the language was the vocalic alternation made significant for number.  And yet consider the following facts.  The change of foti to foeti antedated that of foeti to foete, foet.  This may be looked upon as a “lucky accident,” for if foti had become fote, fot before the _-i_ had had the chance to exert a retroactive influence on the o, there would have been no difference between the singular and the plural.  This would have been anomalous in Anglo-Saxon for a masculine noun.  But was the sequence of phonetic changes an “accident”?  Consider two further facts.  All the Germanic languages were familiar with vocalic change as possessed of functional significance.  Alternations like sing, sang, sung (Anglo-Saxon singan, sang, sungen) were ingrained in the linguistic consciousness.