Note that the flow through each of the dashed edges is at full capacity: this is the 'bottleneck' of the system. By contrast there is spare capacity in the right-hand part of the network. In particular, the flow from node one to node two need not be equal to 1. If there were no flow between nodes one and two, then the inputs to the sink would change to 4/4 and 3/5; the total flow would still be seven (4+3=7). On the other hand, if the flow from node one to node two were doubled to 2, then the inputs to the sink would change to 2/4 and 5/5; the total flow would again remain at seven (2+5=7).