Then, Sir, as to Bribery and Corruption at Elections ... every Elector has a natural Byass to vote for one Man rather than another, and every Elector will vote according to his natural Byass, if he is not bought off: whoever endeavours to buy him off, must certainly come up to his Price, and this Price will be higher or lower, according to the Elector's Honour and Circumstances, and the natural Byass he has for the other Candidate. A great many Men may be perhaps bought off with 100 or 1000 Guineas, who, if half that sum were offered, would spurn it away with an honest Disdain.
Source: wiktionary