“The dialectic is the play that the last instance opens up
between itself and other ‘instances’, but this dialectic is
materialist: it is not played out up in the air, it is played out
in the play opened up by the last instance, which is material.”
— Louis Althusser, as quoted by Christopher Bray at
https://thecritic.co.uk/issues/february-2020/inveterate-ignoramus/
See also Althusser in this journal.