This quote suggests a cynical view of the value of communication, specifically written communication. It implies that most of the letters the speaker has received have not been worth the cost of their delivery, either in terms of monetary value or the effort and time spent on reading them. The speaker is expressing disappointment, or perhaps frustration, at the lack of meaningful, valuable or impactful communication they have experienced.

In a broader sense, this quote can be interpreted as a commentary on the quality and depth of human interactions. It suggests that many of our exchanges are superficial, trivial, or lacking in substance or value. The "postage" could be seen as a metaphor for the time, effort, and emotional investment we put into our relationships and interactions. From this perspective, the quote is a call to strive for more meaningful, substantial, and worthwhile communication.

Applying this concept to today’s world, it’s easy to see parallels with our current communication landscape. In the age of social media, emails, and instant messaging, we are inundated with a constant stream of communication. However, much of this is trivial, superficial, or lacking in depth and substance. Just as the speaker laments the lack of valuable letters, we may find ourselves frustrated or overwhelmed by the volume of meaningless or unimportant messages we receive.

In terms of personal development, this quote could serve as a reminder to strive for depth and substance in our own communication. It can encourage us to focus on quality over quantity in our interactions, to take the time to craft meaningful messages, and to seek out and nurture relationships that offer more than superficial exchanges. It also reminds us to value and appreciate the rare instances of truly meaningful communication we receive.