Up these they wrought their way with indescribable
difficulty and peril, in a zigzag course, climbing from rock to rock, and helping their horses up after them; which scrambled among the crags like mountain goats; now and then dislodging some huge stone, which, the moment they had left it, would roll down the mountain, crashing and rebounding with terrific din.
And it seems to me that nothing less than a long list of such cases is sufficient to lessen the difficulty in any particular case like that of the bat.
Therefore, I can see no difficulty, more especially under changing conditions of life, in the continued preservation of individuals with fuller and fuller flank-membranes, each modification being useful, each being propagated, until by the accumulated effects of this process of natural selection, a perfect so-called flying squirrel was produced.
Although no graduated links of structure, fitted for gliding through the air, now connect the Galeopithecus with the other Lemuridae, yet I can see no difficulty in supposing that such links formerly existed, and that each had been formed by the same steps as in the case of the less perfectly gliding squirrels; and that each grade of structure had been useful to its possessor.
Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.
Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.
With these facts, here far too briefly and imperfectly given, which show that there is much graduated diversity in the eyes of living crustaceans, and bearing in mind how small the number of living animals is in proportion to those which have become extinct, I can see no very great difficulty (not more than in the case of many other structures) in believing that natural selection has converted the simple apparatus of an optic nerve merely coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the great Articulate class.
Let any one now consider with that little
difficulty the king could have maintained his position in Italy had he observed the rules above laid down, and kept all his friends secure and protected; for although they were numerous they were both weak and timid, some afraid of the Church, some of the Venetians, and thus they would always have been forced to stand in with him, and by their means he could easily have made himself secure against those who remained powerful.
The zeal for attempts to amend, prior to the establishment of the Constitution, must abate in every man who is ready to accede to the truth of the following observations of a writer equally solid and ingenious: "To balance a large state or society [says he], whether monarchical or republican, on general laws, is a work of so great
difficulty, that no human genius, however comprehensive, is able, by the mere dint of reason and reflection, to effect it.
Visual problems can be present in both 'good' and 'poor' readers; it is generally accepted that they are not the cause of reading difficulties but have been found to be correlates of reading
difficulty. (1,2) However, visual problems may result in a child finding reading uncomfortable resulting in a reluctance to read or
difficulty reading for long periods.