If it is true that...

Sections of the ruling class are precipitated into the proletariat or threatened in their conditions of existence by the advance of industry

Then it must be true that...

The proletariat is the only really revolutionary class in face of modern industry

If it is true that...

The bourgeoisie finds itself in a constant battle with various groups including foreign bourgeoisie

and

Sections of the ruling class are precipitated into the proletariat or threatened in their conditions of existence by the advance of industry

Then it must be true that...

The proletariat is the only really revolutionary class in face of modern industry

If it is true that...

The bourgeoisie finds itself in a constant battle with various groups including foreign bourgeoisie

and

The bourgeoisie supplies the proletariat with its own elements of political and general education

and

Sections of the ruling class are precipitated into the proletariat or threatened in their conditions of existence by the advance of industry

Then it must be true that...

The proletariat is the only really revolutionary class in face of modern industry

If it is true that...

The proletariat is the only really revolutionary class in face of modern industry

Then it must be true that...

The lower middle class fights against the bourgeoisie to save their existence as fractions of the middle class