One of the most well-known theories in the area of paper is probably Page's theory of tensile strength. The article was published in Tappi Journal in 1969 [1], and written, in a very articulate way, to explain how tensile strength is determined by fibre properties and inter-fibre bond properties. Because this is the area of great interest to papermakers and pulp manufacturers, the theory has attracted great attention since then. In particular, many paper chemists were fascinated by this intuitive way of describing the relationships between bond and fibre parameters so that the theory became a theoretical foundation for many investigations of dry/wet strength agents. Interestingly, Derek himself was not completely happy with the popularity of the theory. As he noted in his paper, it is a semi-empirical theory, intended to provide a picture of the essential factors affecting tensile strength, but not as an analytical equation to predict some of the model parameters. (We will briefly touch upon Derek's concerns later.) In the late 70s, Derek and his colleague, Raj Seth, another legendary scientist from Pulp and Paper Research Institute of Canada (PAPRICAN, currently, FPlnnovations), launched investigations of the tensile stress-strain curves of paper [2,3,4]. The work depicted complex interplays among network structures, fibre properties and inter-fibre bond properties, again, in a very articulate way. This paper has also influenced a number of studies by younger researchers in the areas of paper mechanics and network mechanics. In this short article, I will try to describe how Derek tackled the problem of understanding the tensile properties of paper in the simplest and most articulate way. Based on this review, I will comment on how far we have gone from his ideas, and try to define some outstanding questions.