When buying a decent pair of shoes, I often see the statement "with Natural Sole" ("Loafers in Tan Leather with natural sole.") written in the description of the shoe. Does this mean that the shoe's sole is made out of natural materials e.g. various types of wood or does it refer to something else in particular?
Natural Sole means a sole made of natural materials. Leather is a natural material, so "Loafers in Tan Leather with natural sole." are a natural footwear. By adding "natural" the manufacturers mostly imply "allowing the wearer's foot to breathe."
Natural Sole are footwear made of (from) wood, papyrus, palm leaves, (cowhide) leather, ostrich skin, anaconda skin, elephant skin, and even cotton.