Liber played a defining role in the development of the Bund and helped shaped the policies of the leaders of the February Revolution.

Mikhail Isaakovich Goldman was born in the Lithuanian city of Vilnius, then part of the Russian Empire, into a secular Jewish family.

He took an interest in the plight of Jewish workers in the Russian empire and joined the General Jewish Workers' Union in Lithuania, Poland and Russia (Algemeyner Yidisher Arbeter Bund in Lite, Poyln un Rusland, אַלגעמײַנער ײדישער אַרבעטער בונד אין ליטע פוילין און רוסלאַנד) in 1897.

He defended the Bund's demand to be recognised as an autonomous organisation within the RSDRP and as the sole legitimate representative of the Jewish proletariat in the Russian empire.

Martov had himself been a member of the Bund in the 1890s and one of Liber's former collaborators, but at the second congress, he supported Lenin in demanding the integration of the Jewish proletariat in an All-Russian Social-Democratic party.

During the abortive Revolution of 1905, Liber played a role as a Bundist representative in the soviets, even though he, like most SDs (including Lenin), initially greeted the new, spontaneous workers' organisation with some scepticism.

When the Revolution petered out in 1907 and the autocracy reasserted its authority, Liber was one of those who advocated a more cautious, legalistic course of action for the RSDRP.

Zenzinov and N.D. Avksentiev - so closely that his name was often linked in Bolshevik propaganda with those of Dan and Gots, in a pun on the German phrase Dann lieber Gott!

Liber was a staunch supporter of Alexander Kerensky's Provisional Government, although he declined an offer to join the cabinet, preferring to concentrate on his work in the soviet.

[citation needed] Liber opposed the October Revolution of 1917 and rejected the position taken by the Mensheviks and many Bundists, which called for negotiation with the Bolsheviks for the purpose of forming an all-socialist coalition government.

Liber, for opposite reasons, agreed with Lenin that a unity government uniting the Bolsheviks with the moderate socialists they had just overthrown was politically impossible and would destroy the revolution.

Owing to his anti-Bolshevism, Liber lost his leadership positions in the Menshevik party and in the Bund, but found himself in agreement with anti-Bolshevik SRs like Gots and Avksentiev.

However, Soviet sources deny this and claim that Gots lived until 1940, while Liber retired from politics, devoted himself to business and died of natural causes.