The key factor that enabled the spread of the Renaissance throughout Europe was the invention and dissemination of the printing press, developed by Johannes Gutenberg in the mid-15th century. This technological advancement facilitated the rapid production of books and pamphlets, making literature, scientific texts, and humanist writings more accessible to a broader audience. The printing press amplified the exchange of ideas across borders, allowing Renaissance thinkers to share their work widely, which fostered intellectual discourse and cultural exchange. As a result, the Renaissance ideals of humanism, art, and science could thrive and spread beyond Italy, influencing various parts of Europe significantly.