Peter Drucker had several notable quotes about learning, including the idea that it’s a lifelong process necessary for adapting to change and that “Knowledge has to be improved, challenged, and increased constantly, or it vanishes“. He also famously stated that in the 21st century, “The only skill that will be important… is the skill of learning new skills. Everything else will become obsolete over time”. 

Here’s a few favorites

• On the necessity of continuous learning:“Knowledge has to be improved, challenged, and increased constantly, or it vanishes.”
• On lifelong learning: “Learning is a lifelong process of keeping abreast of change,” and “the most pressing task is to teach people how to learn.”
• On future skills: “The only skill that will be important in the 21st century is the skill of learning new skills. Everything else will become obsolete over time.” 
• On the power of teaching: “Just as no one learns as much about a subject as the person who is forced to teach it.”
• On the importance of reflection: “Follow effective action with quiet reflection. From the quiet reflection will come even more effective action.”