Marie, you are on target with your conclusion. That which is first is physical. That which is second is spiritual. "Marvel not..." Jesus said. When "natural" is contrasted with "spirit," the "birth" or resurrection comes into view. "Natural" and "flesh" are many times interchanged with each other. The "natural" and "flesh" have to do with the "old nature." "Spirit" has to do with the "new nature." Natural is connected with spiritual death. Whereas spirit is connected with spiritual life.