The assignment provided consists of two essays on the topic of sustainability models in businesses. The first essay discusses the necessity of having a sustainability model for all organisations to maintain strong and long-run sustainability at large scale. It also introduces specific models such as 'Australian Ecologically Sustainable Development' and 'Natural Step' process, as well as three types of sustainability models: overlapping-circles model, nested-dependencies model, and legged stool model. The second essay presents an alternate view that all sustainability models are essential and effective for businesses to achieve better results and outputs within a predetermined time period. It highlights the benefits of perfect sustainability models in achieving competitive advantages and maintaining better reputation in the market effectively.