There are some who think libraries are simply “warehouses for books,” when in fact they’re more akin to thesauri. Roget had nothing to do with the first thesaurus, as the Greeks meant it. The first compilation of synonyms was by Philo of Byblos, a Phoenician scholar, in 125 CE. Philo’s book proved so useful a tool for political, commercial, and other types of communication that he named it “Thesaurus,” which meant “Treasury.”

All good libraries are precious, but “storehouse” does fit large, retrospective research libraries, like those at universities. Their students often need to study how ideas evolve over time, so even dated materials can be useful. Public libraries’ users want the latest information on repairing septic systems, cleaning moose, and airplane ticket prices rather than historical overviews, so public library collections are carefully chosen and culled for relevance to facilitate quickly locating the most current and useful information.

It’s misunderstood like your appendix. Long thought to be a vestigial organ of no practical use, Duke University researchers proposed several years ago that the human appendix harbors a collection of bacteria essential for healthy digestion and “acts as a safe house for good bacteria. The body uses this to essentially “reboot” the digestive system when one suffers from a bout of dysentery or cholera.”

Charles Darwin thought our appendices originally helped digest grasses and gradually withered as our diets expanded to include fruits and meats. He was wrong about humans, but koalas are notable for their unusually long appendices that are necessary for digesting tough eucalyptus leaves. We also know koalas yawn, and quite cutely, but not contagiously. “Yawn” comes from the Old English “ginian,” meaning “to open the mouth wide.” Most animals yawn, with insects being the big exception, but not all of them can emit contagious yawns like humans and chimps. Yawning’s built-in, like breathing, and has ancient roots. “You don’t decide to yawn. You just do it. You’re playing out a biological program,” neuroscientist Robert Provine says in “The Surprising Science of Yawning,” a recent NewYorker.com article by Maria Konnikova.

Researchers think yawning is something our bodies do to perk up and transition from one form of activity to another, and only humans and chimps are capable of causing others to yawn by yawning. Moreover, researchers have found that we’re more likely to yawn when we’re empathetically linked to the person yawning. The tendency of humans and chips to yawn increases when they see yawns from someone yawn who’s of their own race or is familiar. However, while we’re less likely to do so when we’re older, autistic, or schizophrenic, yawning can also be induced by merely reading about it.

Another recent article goes into animals’ dreams. BBC.com’s Jason Goldman wrote last month about French studies from the 1960s showing that when the pons area of cats’ brainstems are disabled, they physically act out their dreams of stalking and hunting. The pons paralyzes our muscles during REM sleep, and “injuries are common” among sufferers of REM Sleep Behavior Disorder who experience “punching, kicking, leaping, and running from the bed during attempted dream enactment.”

Scientists are able to watch the brain neurons fire in sleeping rats’ brains and know precisely where they’re dreaming they are in their training mazes. Others have found that zebra finches “are not born with the melodies of their songs hardwired into their brains,” and must learn their songs after birth. Afterwards each note corresponds to a certain neuron firing, so researchers can tell what notes and songs they’re “practicing” while asleep.

Speaking of snoozing, there’s “Babies Cry At Night to Prevent Siblings, Scientist Suggests,” a ScienceNews.com article by Laura Sanders. The scientist in question is evolutionary biologist David Haig, who posits a “sinister suggestion: The baby who demands to be breastfed in the middle of the night is preventing his mom from getting pregnant again … beyond libido-killing interruptions and extreme fatigue, frequent night nursing also delays fertility in nursing women.”

Reading an interesting yet challenging book or listening to gentle music are good ways to compose your mind for sleep. And your library, that gymnasium of the brain and necessary source of respite and understanding, is packed with both.