ɐkˈoːɹdɪŋ tə hˈiːkəl skˈɑːlɚɹ ˈoʊlæf bɹˈeɪdbɑːx, ðə wˈɜːk wʌz "nˌɑːt dʒˈʌst ɐ bˈʊk ʌv ˌɪləstɹˈeɪʃənz bˌʌt ˈɔːlsoʊ ðə sʌmˈeɪʃən ʌv hɪz vjˈuː ʌvðə wˈɜːld."
According to Haeckel scholar Olaf Breidbach, the work was "not just a book of illustrations but also the summation of his view of the world."