a bit about wabisabi
First of all, what is an "aesthetic?" It's a theory or philosophy of beauty. One of the most immediate, obvious characteristics of Japanese culture is the concern placed upon design and art. The Japanese expression wabi sabi is a few centuries old, and it conveniently encapsulates many of the values we have come to associate with traditional Japanese aesthetics.
The translation of wabi is "lonely." According to author Boyé Lafayette De Mente, in current usage it means: "a taste for the simple and the quiet." It is associated with the internal and spiritual in the context of wabi sabi.
sabi actually means "rust." It is the external and material aspect of the wabi sabi whole.
The person credited with combining the words wabi and sabi into a phrase is the poet Matsuo Bashō. Bashō is most famous for inventing the haiku poetry form. The haiku, in just seventeen syllables, attempts to connect the reader with a fleeting moment or thought, often in a poignant or light-hearted manner. The images evoke nature in its ever-changing flow. In his lifetime of pilgrimages throughout the countryside, Bashō often stayed in Zen temples, and also wore the robes of a Buddhist priest (although he was never a practicing priest), so more than just a hint of Zen philosophy can be seen in his writing.
To get a sense of this somewhat nebulous philosophy, one needs to be aware of, and to appreciate, the impermanence of the material world. In looking at the world around us, an object (manmade or in nature) that is unpretentious, earthy or "rustic," simple yet asymmetrical, may be considered wabi sabi. Bonus points for natural materials such as earthenware or wood that have a unique character due to being weathered or worn.
To get a fuller understanding of this aesthetic, it would probably be useful to become a student of one of Japan's many cultural traditions, such as: flower arranging (ikebana), tea ceremony (sadō), Japanese wood flute (shakuhachi), haiku and/or Zen Buddhism. All of these traditions have quite common roots, going back centuries, and collectively represent a big portion of the heart of Japan's rich history and culture. Each one of these interests may take years if not a lifetime to "master," but the process of the experience will definitely create a greater appreciation of wabi sabi!
In recent years, a fair amount has been written about wabi sabi in the Western press. You can find books on interior decorating, philosophy, and even on writing, with a wabi sabi angle. But it can't just be dismissed as a "trend." It is an enduring and appealing way of looking at the world; an antidote to today's too-often prefab and plastic society.