Ultimately, though, this short book holds together impressively, encompassing an astonishing range of modes: vaudeville humour, tragic romance, philosophical speculation.

These paintings address an interior world of philosophical speculation.

As the conversation blossoms, the pair wander blissfully off topic into wider philosophical speculation about the nature of culture, for instance, or humanity's curious relationship with past, present and future.

Conscientious, painstaking research was required, instead of philosophical speculation and unwarranted, sweeping generalisations.

He often veered into philosophical speculation on technology, the nature of intelligence, the impossibility of mutual communication and understanding, and humankind's place in the universe.