A useful analogy might be a worker single-handedly cultivating a very large field. Productivity for this worker could be higher if only a relatively small part of the field were cultivated, yet it is assumed that all the fixed factor (in this case land) must be used. Although the worker tries their best, TP is relatively low. The field is barely dug, planting poor and it proves difficult to keep the weeds down and scare away the birds. The field is not used to its best potential. The fixed factor is severely under-utilised. Bringing in a second worker proves to be beneficial. The additional worker permits a better use of the fixed factor and TP more than doubles. It is possible that a degree of specialization might be introduced, with the two workers fulfilling different tasks. Increasing marginal productivity might continue with the employment of additional labour. However, after a point MP starts to fall. The additional workers are still working hard, but the tasks they fulfil are less productive. For example, taking out relatively small weeds is a full-time job for the marginal worker, yet has is little impact upon TP. It even other’s way and possibly damage the crop.