The phrase "" is an eye opener not only to human pshycology but also to the effusiveness of beauty. If we pick the human beholder as the effective scale of the world's beauty then It stands to reason that some people are bound to find the world less beautify than others. If we expand on that idea then logically beauty is given rise to a by criteria specific to specific human thought I.e. Past influence by observed orders or systems, primal emotions , concious and unconcious desire or other indirect factors all of which can be considered as non-rational. As such if we have a hypothetical human who is perfectly rational in terms of number of non-rational thoughts being zero, it is logical to say that the perfectly rational human won't find the world beautiful or will likely not need the concept of beauty proving beauty was birthed and continues due to processes that are not necesarilly directly rational.
I assume for the sake of argument that unconcious thought, feelings and emotions and other obscure and non direct thought orders are irrational.