Einstein referred to his desk drawer at the patent office as his "office of imagination." The reason he called it this is because, while working as a technical expert at the Swiss Patent Office, he had the opportunity to reflect on and develop his groundbreaking scientific ideas. Although his official job was reviewing patent applications, Einstein used his free time at the office to think about his theories of relativity and other revolutionary concepts in physics.
The “office of imagination” reflects the fact that his work at the patent office provided him with a steady, undemanding job that allowed him the mental space to explore abstract ideas. This period of his life was crucial for his development as a physicist, and many of his most important theories were conceived during this time.