repetitive in form, due to the oral transmitted nature of early Buddhism, nonetheless contains some of the most nuanced and accurate descriptions of the science of the brain and how to reach peaceful restful states.
For experienced meditators, experience validates the Sutta's words, ancient as they may be, they are the most accurate descriptions of meditative mental states we've had.
"Seeing that [the five hindrances] have been abandoned within him, he becomes glad. Glad, he becomes enraptured. Enraptured, his body grows tranquil. His body tranquil, he is sensitive to pleasure. Feeling pleasure, his mind becomes concentrated."