A small river forming the boundary of Italy,which Caesar crossed when he invaded Italy, with theintention of subduing it. Hence "to pass the Rubicon" is totake a desperate step in an enterprise, or to adopt ameasure form which one can not recede, or form which he isdetermined not to recede: (Webster) సాహసమైన ప్రయత్నము చేయడము,ముందరపెట్టినకాలు వెనకపెట్టని ప్రయత్నము చేయడము.