An invention which at first sight appears obvious might in fact involve an inventive step. Once a new idea has been formulated, it can often be shown theoretically how it might be arrived at, starting from something known, by a series of apparently easy steps. The examiner must be wary of ex post facto analysis of this kind. When combining documents cited in the search report, he has always to bear in mind that the documents produced in the search have, of necessity, been obtained with foreknowledge of what matter constitutes the alleged invention. In all cases he must attempt to visualise the overall state of the art confronting the skilled person before the applicant's contribution, and he must seek to make a "real-life" assessment of this and other relevant factors. He has to take into account all that is known concerning the background of the invention and give fair weight to relevant arguments or evidence submitted by the applicant. If, for example, an invention is shown to be of considerable technical value, and particularly if it provides a technical advantage which is new and surprising and which is not merely achieved as a bonus effect in a "one-way street" situation (see G‑VII, 10.2), and this technical advantage can convincingly be related to one or more of the features included in the claim defining the invention, the examiner has to be hesitant in pursuing an objection that such a claim lacks inventive step.