Let's say we have two layers, and . will be the lower layer and it has capsules, and will be the higher layer and it has capsules. Capsules from the lower layer send their outputs to capsules in the higher layer. will be the activations of the capsules from the lower layer, . will be the activations of the capsules from the higher layer, .

The following figure represents a capsule, , and as you can observe, it takes the outputs of the previous capsules, , as inputs and computes its output, :

We will move on to learn how is computed.