Originally Posted by Pappers_
I don't understand - would you say more, please?
He's referring to the fact that dry yeast doesn't really need to be aerated, whereas liquid yeast (or repitched yeast from ANY source) does.
However, experiments done by the yeast companies to determine dissolved oxygen levels using various methods of aeration/oxygenation have concluded that "stirring" (and similar methods) is the absolute worst method, and barely gets any O2 into solution... so it's really a piss-poor way of getting a "head start", and shouldn't be counted on.
Not to mention the whole issue of HSA (Hot Side Aeration), which many brewers dismiss as "just another brewing boogeyman", despite their being significant merit to the entire concept. Not to mention that said dismissive brewers invariably rely on fallacious logic, and/or a poor understanding of the pertinent science.