A vertical line symbolically connects earth and sky, or physical with spiritual. So when I lift my arms for a sun salutation I reach beyond myself and breathe in, like the branches of a tree seeking the light of the sun. As I fold forward, and breathe out, my hands find the earth at my feet, reminding me of what supports my existence: I have a history here, a past; I walk the earth. When I breathe in again, I gesture horizontally by extending my spine, towards parallel with the ground, in between earth and sky, seeking balance between inspiration and the substance of my path: a present moment synergy where I get it, and know where I am. I belong right here walking the line between physical life and light and inspiration.
An open hand indicates friendliness, is ready to receive, or has nothing to hide. In yoga an open, spreading palm activates energy, cultivates optimism and connects the yogis beyond themselves (into a perception of the yoga mat if the hand is there).
My aim in yoga is to connect FULLY with the HERE and NOW. One of the ways I can do that is by connecting to myself physically within the four corners of my mat or wherever I happen to be practicing. Another way I can cultivate this is by watching for future-tripping and memory-lollygagging. If I see my mind wandering like this then I can bring myself back to where I actually am in the moment by watching my breath or noticing my surroundings or sensations. I can find the anchors in the internal experience or external world.
I strive to live in this moment in this world, rather than living in the past, a future fantasy, or a lie.