Snellen defined standard vision as the ability to recognise a letter (âoptotypeâ) when it forms an angle of 5 arcminutes, which is âline nineâ of the letters (âoptotypesâ) on the chart at 6 metres. Hermann, Dutch ophthalmologist, 1834-1908.
In the context of the theory of Marxist revolutionary struggle, vanguardism is a strategy whereby the most class-conscious and politically advanced sections of the proletariat or working class, described as the revolutionary vanguard, form organizations in order to draw larger sections of the working class towards revolutionary politics and serve as manifestations of proletarian political power against its class enemies.
Historically, radicalism has referred exclusively to the radical left, under the single category of far-left politics, rarely incorporating far-right politics though these may have revolutionary elements; the prominent exception is in the United States where some consider radicalism to include both political extremes of the radical left and the radical right.