Context helps readers guess that "inchoation" in this passage describes experiences that are preliminary and universal.
In the excerpt, the narrator tries to capture the experience that a reader has when he or she encounters with a fascinating and shivering passage. The inchoation, or beginning, (Merriam Webster), represent the start of an enthralling feeling that is preliminary, as it prepares the reader for richer and more important experiences, and could encompass something that is inherent in human life, i.e. universal. A sudden thrill that pulls the strings of the soul and deeply connects with the reader. These experiences are unexpected, and they are the beginning of something much bigger and enriching that may change the reader forever.