The killing blow lands at the temples, and the temple is always the head where the higher mind sits enthroned. Sisera is the exhausted general of the lower nature, the force that has driven and warred and now lies asleep and weary in a person, its energy spent. The still, quieter power that pins him drives a single point through those temples and fastens it to the ground, drawing the running mind down and holding it fixed to the earth of the body.
What war could not stop, stillness finishes while the lower force sleeps. The restless drive dies when the sharp point of attention is set at the seat of thought and held there without moving.
Nail: the single fixed point of attention driven through wandering thought
Temples: the head, the seat of the higher mind where consciousness is enthroned
Tent: the loosely pitched dwelling of the body, temporary and easily struck
Ground: the earth of the body to which the running mind is fastened and stilled