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.
Vladimir Lenin popularized political vanguardism as conceptualized by Karl Kautsky, detailing his thoughts in one of his earlier works, What is to be done?.