This quote suggests that every neurosis, which is a class of functional mental disorders involving distress but not delusions or hallucinations, presents itself as a normal or natural part of life. In other words, these mental disorders are often perceived by the individual experiencing them as a part of their identity or personality, rather than as a condition that needs to be addressed and treated.

This is because neuroses often involve patterns of thought or behavior that are deeply ingrained and habitual. As such, they can feel like an inherent part of who a person is, rather than something external to them. This can make it difficult for individuals to recognize that they have a problem, and even more challenging to seek help or make changes.

Applying this idea to today’s world, we can see that many people normalize their stress, anxiety, or other negative feelings, considering them as a natural part of their daily life. This normalization can often prevent people from seeking help or finding ways to manage their mental health effectively.

In terms of personal development, understanding this concept can be incredibly beneficial. It can encourage individuals to question their own thought patterns and behaviors, and to consider whether they might be suffering from a neurosis that they have come to see as a normal part of their existence. By recognizing that what they perceive as "natural" might actually be a mental disorder, individuals can take steps towards seeking help and implementing changes that can improve their mental health and overall quality of life.

Furthermore, this quote also emphasizes the importance of self-awareness in personal development. By becoming more aware of our own thoughts and behaviors, we can better identify and address any neuroses or other mental health issues we may be dealing with.