Which two statements from the passage best illustrate the central ideas?

For we know that the study of the stars, though undertaken for selfish reasons and pursued in the spirit of charlatanry, led at length to physical science, while the study of dreams has proved as unprofitable as the dreaming of them.

The subject of the significance of dreams, so long ignored, has suddenly become a matter of energetic study and of fiery controversy the world over.

To use Professor Bergson's striking metaphor, our memories are packed away under pressure like steam in a boiler and the dream is their escape valve.

Before the dawn of history mankind was engaged in the study of dreaming.

But the psychologist rarely paid attention to dreams except incidentally in his study of imagery, association and the speed of thought.

For we know that the study of the stars, though undertaken for selfish reasons and pursued in the spirit of charlatanry, led at length to physical science, while the study of dreams has proved as unprofitable as the dreaming of them.

This paragraph is an introduction. the author introduces the topic of study of dreams and stars by telling us some background information.

The subject of the significance of dreams, so long ignored, has suddenly become a matter of energetic study and of fiery controversy the world over.

this paragraph is an elaboration of the topic.

To use Professor Bergson's striking metaphor, our memories are packed away under pressure like steam in a boiler and the dream is their escape valve.

this paragraph is used as an example to support the topic.

Before the dawn of history mankind was engaged in the study of dreaming.

But the psychologist rarely paid attention to dreams except incidentally in his study of imagery, association and the speed of thought.

these paragraphs are sort of like a summary or conclusion