Towards the end of the 18th century, and influenced by the philosophy of John Locke, the granting of patents began to be viewed as a form of intellectual property right, rather than simply the obtaining of economic privilege. A negative aspect of the patent law also emerged in this period - the abuse of patent privilege to monopolise the market and prevent improvement from other inventors. A notable example of this was the behaviour of Boulton & Watt in hounding their competitors such as Richard Trevithick through the courts, and preventing their improvements to the steam engine from being realised until their patent expired.