Complex sentence: Staines is a self described libertarian who described in a 2000 publication how he became a libertarian in 1980 after reading Karl Popper's "The Open Society and its Enemies".
Split into simpler sentences: Staines is a self described libertarian who described in a 2000 publication how he came to the identification. This was realised by reading Karl Popper's "The Open Society and its Enemies".