(...and from other sources but Cliff was crucial and a living link to earlier struggles.)
(i) "Class" is economic, not just social. Those who own only their own labour power (ability to work) have to sell that labour power to those who control the means of production. Thus, class is defined by different relationships to the means of production.
(ii) The buying and selling of commodities, including labour power, is the present, capitalist, form of class divided society.
(iii) Unlike earlier forms, capitalism is dynamic, perpetually re-making itself, thus generating the illusion that it no longer exists. However, eg, white collar workers replace blue collar workers but remain "workers", ie, those who must sell their labour power to survive. I was asked, "Where are the means of production in a school?" The school produces disciplined, literate, numerate workers for factories, offices, shops, public services, armed forces etc so the means of production are the class rooms, desks, writing materials, text books, exercise books, computers, library, sports fields etc. When public transport was nationalised, someone said that it had nothing to do with profit. Public transport moves workers to where they produce or consume so it has everything to do with profit.
(iv) In class society, there is class conflict, whether hidden or open. This is an inherent conflict of material interests between classes.
(v) There is always potential for revolution and revolutionary situations or opportunities, when class conflict intensifies and becomes more open, occur regularly on a global scale.
(vi) Revolution is the seizure of economic and political power by the vast majority, those who must currently sell their labour power to survive. Thus, it is not a minority seizure of political power.
(vii) However, it will not just happen. A minority that understands revolutionary processes can gain mass support in a revolutionary situation and can thus lead the struggle to completion. Otherwise, opportunities come and go and have done.
(viii) Leaders are not rulers. Someone who gives a moral lead against injustice does not and cannot coerce those who follow their lead. The Paris Commune showed Marx and Engels how the majority can control society and can thus prevent their leaders from becoming a new ruling class.
(ix) Revolutionaries must continually promote their ideas and engage in struggle. It is too late to start organising when a revolutionary opportunity occurs.
(x) A revolutionary organisation that is big enough to influence wider numbers can give the lead the makes the difference.