Knocking on wood

　　The english touch wood for luck; americans prefer t he more sounding knock. These actions reflect the early christian worship for the cross. Making contact with wo od is a way of connecting symbolically with this holy a rticle of christianity. Others see the custom as a surv ivor of the mediecal tradition of sanctuary. In the day s when any fugitive could find protection behind the do ors of a church, touching the wood of these doors would be a signal that he was safe.

　　These christian explanations of wood touching, howe ver, may be additions of an older rationale. Tree worsh ip was common in prechristian europe. Oak trees, especi ally, were widely venerated(崇拜) from celtic britain to the eastern mediterranean. Yggdrasill, world, served mu ch the same symbolic function among the pagan(异教的) nors e as the wooden cross has always served for christians. It was seen as the bridge between heaven and earth. Kno cking wood for luck, therefore, was the equivalent, lon g before the christian era, of knocking on heaven's doo r.