Every structure is made of distinct parts. Where these parts connect with one another, it is important to pay special attention how they connect, both visually and mechanically.
Make the connection between parts clearly visible, so that people can appreciate and enjoy how the structure is held together. For example in this Japanese garden bridge, horizontal and vertical members are connected with a clearly visible mortise and tenon joint that is held in place by a clearly visible wooden peg. This interpenetration of forms makes for a more intimate bond between the parts.
Attention to connection between parts is particularly important when one material meets another. A sharp, distinct and uncluttered connection emphasizes and clarifies the differences in the materials.