Paul Klee was born in Münchenbuchsee near Bern on 18 December 1879, the second son of Hans Klee (1849–1940) and Ida Klee (1955–1921), née Frick. His sister Mathilde (1876–1953) had been born three years previously. His father taught music at the Hofwil teachers’ college near Bern, and his mother was a trained singer.

In 1880 the family moved to Bern. It was Paul Klee’s grandmother Anna Catharina Rosina Frick, née Riedtmann, who first taught him the very basics of drawing and colouring.

Klee went to primary school in Bern between 1886 and 1897. He attended grammar school (the Progymnasium and Literarschule) on the school premises of the Progymnasium on Waisenhausplatz. There he would fill his schoolbooks and jotters with caricatures, copy drawings from magazines and calendars, and draw after nature. Klee’s last few years at school were a torture: “I would have absconded from school before the second year, had my parents not prevented it. The school journal which he and two school friends published on leaving school, entitled Die Wanze (The Bug) caused a scandal at the school. Yet it was while he was still at school that the decision to embark on an artist’s career slowly began to mature inside him. For a long time he pondered the question of whether he should become a musician or a painter.

Klee began to keep a diary in 1898. The first entry dates from 24 April. In September he sat his school-leaving exam and graduated from the municipal grammar school. One month later, on 13 October, he moved into a flat in Munich to study at the private art school of Heinrich Knirr, and from autumn 1900 onwards also at the Academy under Franz von Stuck.

In 1899 Paul Klee met the pianist Lily Stumpf (1876–1946) for the first time at a musical soirée.

In 1901 he left Stuck’s painting class, and on 22 October embarked on a six-month field trip to Italy in the company of the Bern sculptor Hermann Haller. He travelled via Genoa and Livorno to Rome, where he rented a room. Faced with Rome’s overwhelming opulence of classical art Klee experienced a crisis of meaning as an artist.

In 1902 Klee proposed to Lily Stumpf. He spent the following four years living with his parents in Bern as he was unable to subsist on his artist’s earnings. His main source of income during that period were engagements as violinist with the Bernische Musikgesellschaft. Klee regarded his stay at his parents’ house as an opportunity to find himself and to mature as a person.

In 1905 Klee travelled to Paris for a fortnight with Hans Bloesch and Louis Moilliet, two childhood friends.

In April 1906 Klee stayed in Berlin for two weeks. On 15 September he married Lily Stumpf in Bern, and two weeks later the newly-weds moved to Munich.

Their son Felix Paul, Paul and Lily Klee’s only child, was born on 30 November 1907.

In spring 1909 Felix fell seriously ill, and Paul Klee nursed him back to health. That year, as in the following years up until 1915, the young family spent its summer holidays in Bern and surroundings, particularly at Lake Thun. In November Klee first came up with the idea of illustrating Voltaire’s Candide although he would only execute the drawings in 1911.

In July 1910 Klee had his first solo exhibition of 56 works. It began at the Bern Art Museum and was later shown at the Kunsthaus in Zurich, the art dealership Zum Hohen Haus in Winterthur, and the Kunsthalle in Basel.

In February 1911 Klee began to catalogue his works to date in a handwritten directory of works. From then on until shortly before his death he would keep a meticulous record of his artistic output. In the autumn he became acquainted with fellow artist Wassily Kandinsky through the intermediary of Louis Moilliet, and was first introduced to the tenets of the Blaue Reiter (Blue Rider) movement. He also wrote critiques of exhibitions and cultural events held in Munich for the Swiss monthly magazine Die Alpen, edited by Hans Bloesch, his childhood friend.

In 1912 Klee was invited to take part in the second Blaue Reiter exhibition by Franz Marc and Wassily Kandinsky, which was held at the bookshop of Hans Goltz in Munich; Klee was represented with 17 works. In April he travelled to Paris for the second time and visited the artists Robert Delaunay, Henri Le Fauconnier and Karl Hofer at their studio.

In 1914 Klee travelled to Tunisia over the Easter period with his artist friends August Macke and Louis Moilliet. The journey took him via Marseilles to Tunis, St. Germain, Hammamet and Kairouan. On his return Klee exhibited with Marc Chagall at Herwarth Walden’s Berlin gallery Der Sturm. In October he presented his latest watercolours, a series created in Tunisia, as part of the Neue Münchner Sezession (New Munich Secession), of which he was a founding member. The assassination of the Austrian heir to the throne in Sarajevo on 28 June marked the outbreak of World War I. On 26 September 1914 August Macke fell at Perthe-les-Hurlus in the Champagne region.

In 1915 Klee met the poet Rainer Maria Rilke in Munich. Klee spent the summer in Bern; on his way back to Munich he visited Kandinsky at Goldach on Lake Constance, who as a Russian national was forced to leave Germany following the outbreak of war.

On 4 March 1916 Klee’s friend Franz Marc was killed on the front near Verdun, an event that had a profound effect on Klee. On 11 March Klee himself was enlisted in the German army as a member of the Landsturm (home reserves). He was first sent to a recruiting centre at Landshut. On 20 July he was transferred to the 2nd Reserve Infantry Regiment in Munich, and in August to Schleissheim, to the recruit flying corps. As a troop transport commander he flew on assignments to Cologne, Brussels and Nordholz (northern Germany).

In January 1917 Klee was reassigned to the Königlich Bayerischen Fliegerschule V (Royal Bavarian Flying School V) in Gersthofen, where he worked as a clerk in the cash department. His exhibition at the gallery Der Sturm in February together with Georg Muche proved a commercial success.

In December 1918 Klee was given leave of absence from active duty until his definitive discharge in February 1919. His diary entries stopped at that time and were not continued. Klee did however revise and edit the diary over the next few years, rewriting it into a type of autobiography.

In 1919, after his final discharge from active duty, Klee rented a studio at Schloss Suresnes on Werneckstrasse in Munich. During the Bavarian government by commissars he became a member on the Munich Council of Visual Artists and was on the Action Committee of Revolutionary artists. At the Stuttgart Academy Oskar Schlemmer and Willi Baumeister intervened in vain on behalf of Klee’s appointment. On 1 October Klee signed a general agency agreement with Hans Goltz, owner of the gallery Neue Kunst – Hans Goltz in Munich.

In 1920 Hans Goltz organised the largest ever Klee exhibition at his gallery, a retrospective comprising some 362 works which ran from May to June. On 29 October Klee was called to the Staatliches Bauhaus in Weimar by Walter Gropius. A fundamental essay on art theory by Klee was published for the first time in Kasimir Edschmid’s anthology Schöpferische Konfession. Leopold Zahn and Hans von Wedderkop published the first monographs on Paul Klee.