Serocki began composing Ad libitum for orchestra in 1973 but before he completed it, he presented the audience with Arrangements for 1–4 recorders in which he tackled a similar composition problem. It was a question of a multi-part open form in music, which he approach for the first time a decade earlier (1963) in A piacere for piano. In Ad libitum Serocki approached it in an extraordinarily sophisticated manner and it is not surprising that the whole creative process took him as much as four years.
The Latin title means that the various components of the work can be put together “at one’s pleasure”. These are both “pieces” numbered from 1 to 5 as the subtitle of the composition suggests, and “small segments” – sections of the “pieces” marked with letters of the alphabet. Their number ranges between 5 and 8. If all large and small segments were to be played in the order in which they are recorded in the score, the sequence would be as follows: 1 (ABCDEF), 2 (ABCDE), 3 (ABCDEFG), 4 (ABCDE), 5 (ABCDEFGH). However, the conductor has a choice and must decide in what order all five “pieces” will be presented and also how their internal, small segments will be arranged.
While the “pieces” differ from one another considerably with regard to their musical-expressive character, the “small segments” remain unchanged. The first “piece” is lively and restless, the second – slow and lyrical, the third – fast and impetuous, the forth – slow, delicate and murmuring, and the fifth – fast and aggressive. No possible sequence of the “small segments” changes the characterological identity of the “pieces”. Thus the sequence of the “pieces” defines the dramatic concept of Ad libitum.
During the premiere of Ad libitum featuring the Norddeutscher Rundfunk Orchestra in Hamburg, which took place on 17 September 1977, Jan Krenz put together, in accordance with the composer’s will, two different versions of the whole. In this he presented two completely different works: one framed by slow “pieces” (fourth and second) and one surrounded by fast “pieces” (fifth and first).