Mercury is the planet of the mind. Our celestial messenger moves quickly through Gemini, his home sign, making sure our anntena is alert to all kinds of helpful & healing information (on a relative level).
On the ultimate level: "What is the mind? It is a phenonmenon that is not body, not substantial, has no form,... no shape, no color, but, like a mirror, can clearly reflect objects." Lama Zopa Rinpoche
Interesting mental exercise to quickly train the mind