44 Nevertheless no one will be surprised, if all difficulties are not yet solved and overcome; but that even today serious problems greatly exercise the minds of Catholic exegetes. We should not lose courage on this account; nor should we forget that in the human sciences the same happens as in the natural world; that is to say, new beginnings grow little by little and fruits are gathered only after many labors. Thus it has happened that certain disputed points, which in the past remained unsolved and in suspense, in our days, with the progress of studies, have found a satisfactory solution. Hence there are grounds for hope that those also will by constant effort be at last made clear, which now seem most complicated and difficult.
Source: Divino Afflante Spiritu (Vatican.va)