After his school-leaving exam (Abitur) in Bern Paul Klee travelled to Munich in October 1898 to train as an artist. He would continue keeping the diary he began in April of that year until 1918. To prepare for the Munich Academy of Fine Arts Klee attended the private art school of Heinrich Knirr from 1898 to 1900. In 1900-1901 he studied for six months under Franz von Stuck at the Munich Academy.

After a six-month field trip to Italy (October 1901 to May 1902) Klee spent the following years in the reclusive environment of his parents’ home in Bern. There, in the quiet, comfortably middle-class atmosphere of the provincial city he worked systematically on his training as artist. Klee pursued a down-to-earth and rigorously disciplined analysis and appropriation of the artistic means he felt would provide the foundations for his art. He was highly self-critical of his own artistic progress. In particular he had serious reservations about his oil painting.

It was only in 1903, when he began a series of etchings entitled Inventionen, that he believed he is working on his first significant body of work. He completed the sequence of 10 etchings in March 1905, and called it his Opus eins (Opus One). While working on his etchings Klee was drawing figure studies, most of them free inventions, many with traits of caricature. Inspired by the nude drawings by Auguste Rodin which had so impressed him in Rome in 1902, he adopted a freer use of the line.

In summer 1905 Klee began to experiment with drawings etched onto blackened glass panels. He used the natural resistance of this unusual medium to achieve new possibilities of artistic expression. Based on these experiments he developed the technique of verre églomisé, which he pursued with varying intensity until 1912.

In 1906 Klee married his fiancée, the Munich pianist Lily Stumpf. Felix Paul, Paul and Lily Klee’s only child, was born in 1907. Klee took charge of looking after the infant while his wife Lily supported the family by giving piano lessons. Klee continued with his experimentation, increasingly with drawings based on nature as of 1907. He now sought to achieve the free personal style of drawing he had been working on without nature as a model (1903–1906) but this time by drawing in nature itself (1907–1910).

During the first 15 years of his work Klee was primarily and almost exclusively involved with drawing. It was only after 1914 that drawings began to lose their predominant status within his oeuvre. Up until 1910 Klee had been searching for his own personal style. Around 1907 he began to move away from a style based purely on drawing, and to experiment with chiaroscuro and the beginnings of colouristic effects using black watercolours. Then as of 1910 he began to transpose his experience of tonality to colour.

1910 marked the end of Klee’s early work, a phase of reclusive, solitary work on a personal style. In August of that year Klee first went before the public with his first individual exhibition at the Bern Art Museum, which as a touring exhibition was also shown at the Basel Kunsthalle and at the dealership Zum Hohen Haus, in Winterthur. His new friendship with Alfred Kubin, who had taken notice of Klee’s work and bought the first drawing in December 1910, also signalled Paul Klee’s growing fame and the start of close relations with artists of the European avant-garde.