There are many opposites in NDT that are used in conjunction. A major theme being about discovering the unity of opposites. It’s like viewing the directions to the Natural Dog School and thinking you can approach either from the east, coming through Botley village, and turn left into Brook Lane, or perhaps arriving from the west, driving through Hedge End, passing Sparshatts garage and then turn right into Brook Lane. The two sides will both bring you to the field, you can use either to find the entrance to the school, but they originate from different places.
This can be used with approaching the exercises in NDT too. There are different ways to tackle the skills, which although sometimes seem contradictory, will bring you to the same place. It can sometimes feel awkward accommodating these contradictions but the combination of both extremes brings about a centred and balanced union. The bark for example can be elicited using hunger and desire, coaxing and cajoling, which then brings forth the bark, or by focusing on the pressure and block, the scary hand or admonishing finger. The two approaches are needed to give the right result, balancing the forces so the dog is centred in the middle. It allows an easy cross-over, an intersection, like a motorway junction, giving an obvious connection to another direction. Pressure turns to release, and a problem can be resolved.