Fig. Illustration of the Bayesian Illumination algorithm, with its individual steps in the molecular optimisation process, proceeding clockwise from the bottom left. Random selection from the physicochemical archive, mutations, and crossovers initiate exploration of the search space. Structural filtering, physicochemical descriptors and niche determination refine molecule selection. Surrogate fitness and acquisition function calculations inform the selection of a single molecule to be compared in direct evolutionary competition with the current occupant of the niche. This algorithm is applied iteratively, in batches known as generations, until a predetermined fitness function budget is exhausted or the algorithm has converged.