The quote highlights the element of secrecy and obscurity that exists within dark pools, which are private exchanges for trading securities. In these environments, only the brokers operating them have knowledge of the transactions, leaving other market participants in the dark about the activities occurring behind the scenes. This lack of transparency can lead to issues of trust and fairness in financial markets.

Michael Lewis's "Flash Boys" explores the complexities of high-frequency trading and the impact of dark pools on market dynamics. The book reveals how these hidden venues can distort true market conditions, benefiting a select few while disadvantaging everyday investors. The underlying theme emphasizes the necessity for greater transparency to ensure a level playing field in finance.