Peale applied Enlightenment principles to nature by creating the first rationally-classified American natural history museum.  Peale was a painter, naturalist, and all-round scientist.  He was a friend of President Jefferson, and saw his naturalist museum as bringing "rational amusement" (a line in the tickets for the museum) to the American citizenry.  Here, Peale depicts himself inviting the viewer-spectator to enter into the edifying museum.

The bones beneath the curtain to the right are mastodon bones.  Jefferson sent Lewis and Clark on their famous expedition, in part, in the hopes of finding living wooly mammoths... which he believed might be still existing somewhere in "Indian" territory across the Rocky Mountains. The birds, etc., in the grid-like boxes are taxidermist specimens. Note Peale's somber expression; we're not supposed to gape at nature with mindless enthusiasm, or bond with it! Rather we should emulate the three sets of viewers in the distance (roughly the middle of the painting):

--a single man, contemplating the exhibit
--a father instructing his son
--a woman, who expresses astonishment at the mastodon bones (mostly hidden from us), but does so with a sort of petite, polite little gasp

"I made a little book, in which I allotted a page for each of the virtues. I rul'd each page with red ink, so as to have seven columns, one for each day of the week, marking each column with a letter for the day. I cross'd these columns with thirteen red lines, marking the beginning of each line with the first letter of one of the virtues, on which line, and in its proper column, I might mark, by a little black spot, every fault I found upon examination to have been committed respecting that virtue upon that day.”

Franklin--exemplar of the American dream, supreme gadget man, and optimistic Founding Father--here applies the Enlightenment belief in order and rationality to engineering the self.  His autobiography was written in several installments, towards the end of the eighteenth-century after the American Revolution for independence from Britain, and when he was an international celebrity for his scientific, literary, and political accomplishments.  He's describing himself as a young man (in his late twenties), who is a little naive and overly optimistic about his ability to transform himself, and yet he also firmly believes in the secular effort to see personality problems/non-virtuous behavior not as a matter of "sin" but one of habit that can be self-changed.