It's sugar maple, not oak, and it gets burned first. You stack the wood, set it alight, bring it down to charcoal, then pack that charcoal into a vat about ten feet deep and drip the new spirit through it slow. Charcoal mellowing — takes days, not minutes. Any baker knows what charcoal does to a smell; this is the same instinct, only running the other way, pulling harshness out instead of putting smoke in.
Jack Daniel died in Lynchburg in 1911, and he never claimed he worked that method out himself. He learned it from Nathan Green, called Nearest, a distiller who had been enslaved and who went on to be the first master distiller at the distillery. Anyway, it's one of the rare cases where the teaching got written down and the name stayed attached to it, which is more than most kitchens manage.
Acer saccharum. Same tree people are out tapping in March with buckets on the trunk, sap running when the nights freeze and the days don't. Takes forty years or so before one's worth tapping, and then it gets burned down to charcoal for this. Patient wood either way.
Rosa, the safe-kicking story gets told like it's in the record book, and nobody's ever shown me the box score on it. Ballplayers have the same genre — guy misses six weeks, and the version you hear in year ten involves a hotel door and a lawnmower.