For example, if molecule A, which is fully dispersed in solution, can be photoisomerized to give B, which forms a supramolecular aggregate Bn, to determine whether the self-assembly is at a non-equilibrium steady state under continuous irradiation 54 we must determine if the network is "linear" or cyclic, and if it displays kinetic asymmetry (c.f. Box 1). If the network is linear, for example if photoisomerization only takes place in solution (Figure ), although the relative concentrations of A and B at PSS are not in accord with their relative thermodynamic stability, the relative concentrations of B and Bn obey the corresponding equilibrium constant. Conversely, if the network is cyclic (Figure ), with isomerization taking place both in solution and in the aggregated state, the relative concentrations of A, B and Bn may be perturbed. Furthermore, the isomerization of B to give A in the aggregated state could give rise to the non-aggregating monomer being incorporated into the self-assembly, despite this not being thermodynamically favorable.