[7] In addition to numerous guest tours in Europe and Asia, he formed the Philharmonie into an ensemble of international reputation.

According to his Stasi documents, his friendship with the painter Kurt W. Streubel [de] was no longer tolerated by the cultural policy of the SED.

[5] In 1962, the relations between Geissler and the Ministry for State Security (MfS) as well as the Verband Bildender Künstler der DDR [de] (VBK) turned cold.

[5] In the mid-1960s, Geißler met the painter and graphic artist Karl Meusel[9] (1912–1986) in whose works he found inspiration for his compositions.

Already after his return from the Federal Republic to the GDR in 1951, Geißler intervened critically and arguably - much to the displeasure of the political leadership.

However, his attitude to party ideology prompted the MfS to launch a comprehensive surveillance and observation process (OV "Antipode") on Geißler.

[11][12] Geißler ran for the 1990 Thuringian state election on the common landesliste [de] of the New Forum, the East German Green Party and Democracy Now and won a mandate.

As the oldest elected member of parliament he chaired the constituent session of the first Landtag of Thuringia on 25 October 1990 in the Deutsches Nationaltheater and Staatskapelle Weimar.

Matthias Büchner tried during the meeting to make himself heard, but was expelled by the president of the Landtag Gottfried Müller after three Ordnungsruf [de] of the hall.