487. Whether the development required inventive skill.

The question whether a development which in fact has been made required inventive skill or was the natural development of the particular art is one of considerable difficulty. Sometimes the intrinsic nature of the discovery itself may be sufficient to establish the inventive skill1, but the general tendency of the human mind is to minimise a discovery after it has been made2, and it is often necessary to have recourse to extrinsic evidence to show that what has been done by the patentee was not obvious3.

If it can be shown that the particular development is one of great utility