Religion as a metaphor for certain kinds of scientific belief; science
personified as a saint saying prayers on a rosary. Science's desire
to repeat tidy, uncomplicated truths is likened to saying prayers by rote,
without thinking about what they really mean, like repeating prayers with
rosary beads. Ironic here, since the scientist would criticize orthodox
religions for accepting supernatural explanations without question.
The speaker implies that this is what science is doing.
Darkness as a metaphor for the spiritual unknown. Science is portrayed historically as enlightening the darkness of superstition. Waking up at night in "hell" and "staring at darkness" suggests being afraid of things one cannot understand or see through. Since science here accepts simple, rigid answers for things, it is never troubled by these kinds of worry; in its room, the candle of enlightenment always shines bright. It is never afraid of the dark.
Nonetheless, the continuation of this figure of speech suggests that
science should be afraid. The candle that lights up this darkness,
unlike the electric light, sounds surprisingly unscientific. And
more importantly, the candle will soon burn out, especially because it
is burning briskly. The metaphor of shedding light in darkness
becomes ironized to suggest the limits of enlightenment. If
the candle burning out is conventionally associated with death, then
the poet is pointing to the darkness the scientist doesn't understand
and maybe should care about after all: what will happen after death.
Seashell as a metaphor for something that cannot be easily interpreted,
whose meaning lies beyond the reach of reason. The roaring
you hear when you put a seashell to your ear is said to be the sound of
the sea; here the sea is described as one you can never get to, and the
roaring is likened to questions that you can never answer. Science
thinks all it has to do is classify and measure things in nature (fish,
stars, etc.). Apparently an object amenable to scientific scrutiny
(in for example the mathematically describable curve of its shape or through
biological classification) the seashell is an object that keeps raising
questions that science cannot answer.