What's happening
Mercury isn't slowing down. Earth is. Or rather: Mercury, the fastest classical planet, is being overtaken in the way a faster highway lane appears to fall behind when a slower lane catches up to it for a moment. From our vantage, this shows up as an apparent reversal — the planet's ecliptic longitude decreases for about three weeks — before Mercury "stations direct" again and resumes its usual forward march.
The station itself is the pivot: the moment when Mercury's apparent speed passes through zero on the way to negative. Around it, Mercury is effectively standing still against the fixed stars.
The tradition
Classical astrology has never treated retrograde as inherently bad; it treats it as a shift in posture. Mercury's usual business — messages arriving, decisions getting made, commerce moving forward — is understood to slow, double back, and ask to be checked.
The three R's that circulate in contemporary readings — revise, revisit, reconsider — are shorthand for a much older intuition: the signal is noisier than normal, so verify before you send. This is not superstition so much as practice. Contracts signed in haste, inboxes answered without reading them twice, transit cards you forgot to tap — these are the kinds of things that genuinely get worse when attention is drifting, and a retrograde period is one of the few cultural containers we have for paying attention to attention.
How to work with it
Treat it as permission to slow the cadence of decisions that can be slowed, and do not treat it as an excuse to avoid the ones that can't. Ship the release. Have the conversation. But proofread the email, call the airline, and assume the first version of a plan will need a second pass.
The station retrograde is the opening of that window. The station direct, roughly three weeks later, is the close.
The simple rule
Mercury does this three, sometimes four, times a year. Whatever this particular cycle surfaces, another one is coming — the pattern is not a test you can fail.