The author claims the law is a normative system intended to regulate human activities, not just an estranged, recluse and self-absorbed order. The law adapts to the significantly changing reality, otherwise its reality non-reflecting norms become obsolete.
To cope with the changing reality, international law encompasses e.g. clausula rebus sic stantibus as well as the derogation norms. The one deciding these exeptions, it the sovereign.