Why do left and right signal different ends of a political spectrum?
Today the terms left wing and right wing are used as symbolic labels for liberals and conservatives. They were originally coined in reference to the physical seating arrangements of politicians during the French Revolution.
Historic incidents behind this term
As the French Revolution gained steam, an angry mob had just stormed the Bastille. The National Assembly assembled to act as the revolution’s government and the assembly had a principal goal writing a new constitution.
In the year 1789, members of the French National Assembly met to begin drafting a constitution. These sessions were moderated by a Presiding Officer. During the course of deliberations, delegates were deeply divided over the issue on how much authority King Louis XVI should have.
As the debate raged, the two main factions each staked out territory in the assembly hall. The anti-royalist revolutionaries seated themselves to the presiding officer’s left, while the more conservative, aristocratic supporters of the monarchy gathered to the right.
The divisions only continued during the 1790s, when newspapers began making reference to the progressive left and traditionalist right of the French assembly.
About the left
From each according to his abilities; to each according to his needs – Karl Marx
About the right
Man is not free unless government is limited – Ronald Regan
Finally Though various political parties are being labelled to one end of this political spectrum, in reality there is no absolutes regarding the same. The reason being, majorty of the political organization do not have strong ideological affiliation.