Editing Consonant gradation (section)

====Historical sound changes affecting conditions of gradation====

One important change was the loss of word-final *-k and *-h early on in the history of Finnish. This resulted in many open syllables with weak grades. In particular, the majority of nouns ending in ''-e'' are affected by this, with a weak grade in the nominative form. The imperative form of verbs also ended in a now-lost ''-k''. For examples, ''side'' 'bandage', from *''siðe'', earlier *''siðek'' (cf. Veps ''sideg'', Eastern Votic ''sidõg''); {{lang|fi|hakea}} 'to get' → ''hae!'' 'get! (imp.)' from *''haɣe'', earlier *''haɣek''. Traces of the original syllable closure can be seen in [[sandhi]] effects: these classes of words can still be analyzed to contain the assimilative word-final 'consonant' ˣ, realized as lengthening of the next word's initial consonant. Therefore, ''hae side varastosta'' 'get a bandage from storage!' is pronounced {{IPA|[hɑe‿sːide‿ʋːɑrɑstostɑ]}}, where the weak grades indeed occur in closed syllables.

The loss of ''-k'' combined with loss of ''d'' gave rise to the modern Finnish infinitive ending, which was historically *''-tak/täk''. The final *''-k'' triggered gradation, so that the ending normally became *''-dak/däk''. In turn, following the loss of ''d'' between unstressed vowels, and the loss of final *''-k'' only *''-aˣ/äˣ'' remained. Thus, {{lang|fi|hakea}} (originally *{{lang|fi|hakedak}}) has only ''-a'' as the ''d'' was lost. But in verbs like ''juo-da'' 'to drink' the /d/ remained since it followed a stressed syllable. In the case of verbs like ''tulla'' 'to come', the earlier form was *''tul-ðak'', but the ''*ð'' was assimilated to the /l/ according to the patterns described above. The original strong grade was preserved in verbs like ''hais-ta'' 'to stink' since gradation did not take place when a consonant followed /s/.

The situation appears differently in the many verbs ending in ''-ata/ätä''. These verbs seem to have preserved the strong grade in the infinitive ending, going counter to the rules of gradation. However, historically it is in fact a weak grade: the stem of the verb itself ended in *''-at/ät-'', and this is still visible in the 3rd person imperative ending ''-atkoon/ätköön''. Thus, when combined with the infinitive ending, the verb ended in *''-attak/ättäk'' (similar to the origin of the ''-ton/tön'' suffix described above). The ''-k'' then weakened the consonant from a geminate *''-tt-'' to a single *''-t-'', and later loss of ''-k'' resulted in the final form ''-ata/ätä''. However, even though this is now a single consonant, it was originally a geminate and therefore triggers the weak grade on the syllable before it. So whereas the infinitive may be for example ''hypätä'' 'to jump', its original stem was *''hyppät-'', as can be seen in the first-person singular form ''hyppään'' 'I jump', from earlier *''hyppäðen'' with loss of ''*-ð-''.

An opposite effect was caused by the loss of *''h'' and *''ð'' between unstressed vowels. Loss of ''h'' affected nouns and adjectives ending in *''-s'' or *''-h'', such as ''kuningas'' 'king'. In the nominative, this ''-s'' appeared as usual, and as the preceding syllable was closed, the weak grade ''ng'' appeared. But when a case ending such as the genitive {{Not a typo|''-(e)n''}} was added, the result was originally *''kuninkasen'', which was then weakened to *''kuninkahen'', and the loss of ''-h-'' then resulted in the modern form ''kuninkaan''. The intermediate steps are seen in ''mies'' 'man'. Here, following a stressed syllable, the ''-h-'' was not lost, so that its genitive is ''miehen''.

Similar changes affected the illative ending, which was ''-hVn'' where V was the same as the vowel preceding the ending. The ''h'' is preserved after stressed syllables, as in ''maahan'' 'into the land' (from ''maa''), but lost otherwise as in ''kotiin'' 'into the home' (from earlier *''kotihin'', from ''koti''). This explains why ''kotiin'' retains a strong grade even though a closed syllable follows it. The Pohjanmaa dialect of Finnish retains the ''-h-'', however.

Words that now end in ''-e'' are in fact very similar to those ending in ''-s''. These originally ended with ''-k'' or ''-h'' so that the nominative ended in a consonant just as ''kuningas'' and therefore the preceding syllable was in the weak grade. But after an ending was added, the weak grade ''g'' appeared, which eventually disappeared just as ''h'' did.