Definition.com
The Omen is not as senseless as it seems and is in fact a symptom rather than a sign. When an ancient roman stumbled on the threshold as he left the house, he gave up his plans for the day. But, in truth, when one is not in full control of oneself, one's bodily movements may be under a certain constraint... one's attention is easily distracted... one is somewhat absent-minded. As a result one knocks against something, stumbles, lets something fall, or forgets something.
See also
.com