Applied mathematics gives or at least aims to give true descriptions of empirical n particular physical phenomena that are located in space and time. But "true" does not necessarily mean "complete". For example, I spill my glass of milk and it spreads across the table. Applied mathematics successfully describes how it flows, in terms of relevant physical quantities, such as the positions, velocities and densities of small volumes of the milk. But we neglect myriad details, for example the atomic constitution of the milk. Of course, this is done by modelling the milk as composed of volumes that are large enough to contain many atoms (and so, we hope, to be unaffected by atomic phenomena); but which are also small by our human standards, so that the milk seems to be continuous in its make-up. The crucial feature of this example is the mention of "relevant physical quantities": position, velocity and density. Of course, it is one of the great glories of physics since Galileo's day that it has introduced new quantities and refined old quantities — sometimes in very subtle ways. It has combined the new and the old in a collection of laws and methods that — though fallible, and indeed changing with the passing decades — has gone from one success to another, both in theoretical understanding and in empirical quantitative prediction.We have come a long way from Galileo's "triangles, circles, and other geometric figures". In his day, it was indeed reasonable to hope that physics could manage with just the concepts of geometry (as inherited from the Greeks) and maybe a little more — such as notions of contact or impact, and mass and/or density. But it was not to be. Nature's imagination outstrips ours! So as physics went on to examine successive new domains of phenomena, it had to introduce a succession of new quantities (and has also had to refine old ones). It is these distinctive physical quantities (and of course, their values for the system described) that are mentioned by the symbols in the equations of physics.So to sum up: nowadays, we should revise Galileo's saying. Instead of "Nature is a book written in the language of mathematics", we should say: "Nature is a book written in the syntax of mathematics, but with the semantics of physics".