The roots of bitters (pun intended) were established in much earlier times; there are 8 different recipes for bitters in Byron's Modern Bartenders' Guide published in 1884 (perhaps the "roots" of Bob's interest in making cocktails evolved from exposure to rare books during our days as used booksellers).
Modern day bitters are highly concentrated aromatic flavoring agents made with roots, barks, fruit peels, seeds, spices, herbs, and flowers infused into high proof alcohol. Meant to be used by the drop, bitters are an elegant way to enhance the flavor of a mixed drink without unnecessary dilution, or add a dash of flavor without excess liquid.
Never take a swig out of a bottle of bitters. Fun fact: since bitters are alcohol based and sold without proof of age in grocery stores, a licensing requirement for bitters makers is that bitters must not be palatable to drink as a stand alone liquid. No one would ever guzzle a bottle of bitters! Always add a drop at a time and taste the results before adding more.
When we decided to share our own curated collection of bitters, it was time for a brand and a label; patented tonics and elixirs once sold by pioneer traveling medicine men/snake oil salesmen came to mind. It's a hoot to read the claims, cautions and cures on the labels...
For those who have asked why Dr. Bob is not smiling on the labels, this is your now-you-know moment. Most old photos show traveling medicine men sternly facing the camera in a portrait pose that allowed them to remain still during long camera exposures necessary in the era of early photography. Bob is a retired physician; since bitters in cocktails can be good for "what ails you", our tongue-in-cheek riff off old timey cure-all labels became "Dr. Bob's Bitters." We felt so clever we incorporated the same idea on our seasoning labels.