We ordered all the words in The Complete Poetical Works of Henry Wadsworth Longfellow by their frequency of occurrence (the content word vector). The first eight words are:
0.207 old
0.174 man
0.171 see
0.168 day
0.165 heart
0.164 said
0.160 come
0.157 night
Find the text and explore the frequencies (select the text in the Books tab and examine the word list in the Words tab/click on ‘frequency’) here.
More on the Content Word Vector and the Function Word Spectrum.