For me this sort of thing is what makes Marxmail
a great resource. Thanks to everyone who replied.
Summing up:
Lasalle in 1862 wrote:
"Alle gro?e politische Aktion besteht im Aussprechen dessen,
was ist, und beginnt damit. Alle politische Kleingeisterei
besteht in dem Verschweigen und bem?nteln dessen, was ist."
Which translates into English as:
?All great political action consists of and begins with,
speaking out about that which is. All political petty-mindedness
consists of being silent and covering up that which is.?
Luxemburg in 1906 paraphrased Lasalle. Possibly she didn't have
the original available and was quoting from memory? She wrote:
"Wie Las?salle sagte, ist und bleibt die revo?lu?tio?n?rste Tat,
immer ?das laut zu sagen, was ist."
Which translates into English as
"As Lassalle said, it is and remains the most revolutionary
act to always 'say loudly what is'".
Part of that appears to have been translated in the Rosa Luxemburg
Reader as the sentence I originally asked for help identifying:
"The most revolutionary thing one can do is always to proclaim
loudly what is happening."
And just to complicate things, in 1933 Trotsky also paraphrased
Lasalle: "Ferdinand Lassalle, who was no stranger to opportunism
or adventurism, nevertheless expressed perfectly well the
fundamental requirement of revolutionary politics: 'Every great
action begins with the statement of what is.'"
Thanks again
Ian Angus