This is the year when the first of the two
volumes entitled "Volkslieder" ("Folk Songs")
was published by Johann Gottfried von Herder (born
in 1744, in Mohrungen,
Eastern
Prussia, died on 18th December 1803, in Weimar) ). Thus was introduced
the very term, having become commonplace now. After the authors
death a new edition was published in 1807, bearing the better
known title of "Stimmen der Völker in Liedern"
(The Voices of the Nations in Songs).
Herder's teacher Johann Georg Hamann acquainted him
with the MacPherson's
cycle of Ossian,
and possibly also the singing traditions of the local people,
thus providing the thinker with the first examples of nations'
characters expressed in poetry. The influential work by MacPherson
was not the only basis for Herder's ideas, though.
Herder's idea was to look for a nation's expression
in both what we call folklore (the term was not yet coined in
Herder's time) and the authors' poetry. He was not interested
in musical aspects of the songs, thus the idea of "folksong"
becam a textual entity and to a great extent has remained so in
Latvian tradition. From 1764 till 1769 Herder worked in Riga as
the Rector of the Dome School; during this period he allegedly
heard more of Latvian singing thus becoming more impressed by
it and possibly this strengthened his views.
In "Folk-Songs"
there are short passages on the songs of the particular nation
and translations of texts into German. One will find both description
and samples of Latvian poetry there (in some case the texts might
be actually not Latvian, but letð leave that aside!) Herder
is neither the author of the description, nor the translation,
as one will find references to "Gelehrte Beiträge"
magazine, issue of 1764. Whatever the details, still this is supposedly
the first case of Latvian folksongs being included in a collection
on European scale.
And to get the idea what it looks like - some pages:

