This quote implies that success in society doesn’t necessarily depend on intelligence or talent, but rather on the ability to navigate social norms and expectations with grace and politeness. It’s a somewhat cynical view, suggesting that even a lack of intelligence can be overlooked if one is well-behaved and adept at social maneuvering.

The ‘stupidity’ mentioned here does not necessarily refer to a lack of intellectual capacity, but rather a lack of cunning or manipulative intent. It’s about being straightforward and sincere, even if it’s perceived as naive or simple-minded. The ‘well-mannered’ part is about knowing how to behave in different societal settings, understanding and respecting the unspoken rules and norms, and treating others with courtesy and respect.

Voltaire’s quote is quite relevant in today’s world. In the era of social media and global connectivity, where personal branding and image management are crucial, being well-mannered or socially adept can often open doors that intelligence or talent alone cannot. It’s about the ability to network, build relationships and create positive impressions.

Moreover, in personal development, this quote can serve as a reminder to not solely focus on enhancing one’s skills or knowledge, but also on developing social graces and emotional intelligence. It emphasizes the importance of soft skills like communication, empathy, and respect for others, which are increasingly valued in both personal and professional spheres.

However, it’s important to note that being ‘stupid’ and ‘well-mannered’ should not be an excuse for complacency or lack of self-improvement. Instead, it should be seen as a call to balance intellectual pursuits with social finesse for a well-rounded personality and successful life.