Mendelssohn Felix wrote many “Songs without Words” during his lifetime. We can assume that he did not want to give these pieces names because he wanted listeners to experience the music without some kind of expectation due to a title. While this may be a very good idea artistically, it makes it very difficult to describe the music. because there is no handy label.
We are free to imagine anything as we hear these pieces.
This gave me a huge problem regarding pictures. With no title I could not pick a subject, and without a subject I could not start to search for pictures. These songs obviously have no words, since only a singer can use words, so I assume he had in mind the idea of vocalists singing beautiful melodies. For that reason I picked pictures of famous singers as a unifying theme.