Ergo, It is a fancy way to say 'Therefore' or simply 'so'. However, this author, as you know, loves something platonic and flowery. Those three words are usually used to start a conclusion, (They serve their function as linking words). Thus, this book presumably can be taken as a public diary where all the conclusions in the author's mind are put into words. Ergo, I open for you to the door of my mind.