One of the central themes which is definitely conveyed through the character of Pi is the way that the essence of life is shown to be in the details. Again and again, through his observations of life and what he notices going on around him, Pi is a character who notices the details of life and is alive to their wonder and joy. Note the following description of the dying dorado Pi has just caught:
The dorado did a most extraordinary thing as it died: it began to flash all kinds of colours in rapid succession. Blue, green, red, glod, and violent flickered and shimmered neon-like on its surface as it struggled. I felt I was beating a rainbow to death.
In a sense, the highly detailed descriptions that he gives during his time on the ocean are what keeps him alive and sane as he does not abandon hope and give in to despair, but is able to cling on to the simple pleasures of life and his childlike wonder of all that he sees. This is in a sense why the number of lists are so important to Pi's survival and his account. Again and again, Pi's character demonstrates the truth of how the essence of life is in the details.