The formation of a language community in a planned language is one of the most important steps in its development. Esperanto is the only fully functional language with relative success among more than one thousand planned language projects. Model texts have played a very significant role in the development of Esperanto. Esenco kaj estonteco de la ideo de lingvo internacia (Essence and future of the international language idea) by the founder of Esperanto, L. L. Zamenhof, is an important document on Esperanto. Taking the essay as the research object, this paper carries through lexical and syntactical analysis on Esperanto by adopting the research methods of quantitative linguistics and complex networks. The results show that the morpheme distribution of Esperanto follows a power law, word frequency distribution fits Zipf's Law, word length distribution is an exponential curve, and word class distribution obeys linear law. It is also clear that Esperanto is a language with SVO word order preference, the mean dependency distance of Esperanto is 3.85, and the distribution of the dependency distance tends to a minimum, making it typologically a head-middle language. A 43.6% dependency relation appears in adjacent words. The complex syntactic networks of Esperanto display the characteristics of small-world, scale-free networks. All of these quantitative characteristics of Esperanto demonstrate that it is structurally a normal human language