Next to Rieger's short essay the most important contribution made to the accurate and scientific study of alliterative verse was that made by Sievers in his article on the rhythm of the Germanic alliterative verse.[47] In this he shows, to use his own words, 'that a statistical classification of groups of words with their natural accentuation in both sections of the alliterative line makes it clear that this metre, in spite of its variety, is not so irregular as to the unaccented syllables at the beginning or in the middle of the verse as has been commonly thought, but that it has a range of a limited number of definite forms which may be all reduced to five primary types.' These five types or chief variations in the relative position of the accented and unaccented syllables are, as Sievers points out, of such a nature and so arbitrarily combined in the verse, that they cannot possibly be regarded as symmetrical feet of a line evenly measured and counted by the number of syllables. 'The fundamental principle, therefore, of the structure of the alliterative line, as we find it in historical times, is that of a free change of rhythm which can only be understood if the verse was meant to be recited, not to be sung.'[48] Soon after the publication of Sievers's essay on the rhythm of the Germanic verse, the first part of which contained a complete classification of all the forms of the line occurring in _Beowulf_, other scholars applied his method and confirmed his results by examining in detail the other important Old English texts; Luick dealt with _Judith_,[49] Frucht with the poems of Cynewulf,[50] and Cremer with _Andreas_, &c.[51] Sievers himself, after contributing to the pages of Paul's _Grundriss der germanischen Philologie_ a concise account of his theories and results, expounded them in greater detail in his work on Old Germanic Metre[52] in which he emphasizes the fact that his five-type theory cannot properly be called a theory at all, but is simply an expression of the rules of the alliterative verse obtained by a statistical method of observation. In spite of the criticisms of his opponents, Möller, Heusler, Hirt, Fuhr, and others, he maintained his former views. In principle these views are in conformity with the manner of reading or scanning the alliterative verse explained by English writers on the subject from the sixteenth century downwards, though their terminology naturally is not the same as Sievers's. We may, therefore, accept them on the whole as sound.