Here, certainly, is a question of conscience in the usual present sense of the word; and, it may be said, does not this show that all along Hamlet really has been deterred by moral scruples?  But I ask first how, in that case, the facts just adduced are to be explained:  for they must be explained, not ignored.  Next, let the reader observe that even if this passage did show that one hindrance to Hamlet’s action was his conscience, it by no means follows that this was the sole or the chief hindrance.  And, thirdly, let him observe, and let him ask himself whether the coincidence is a mere accident, that Hamlet is here almost repeating the words he used in vain self-reproach some time before (IV. iv. 56): 

                             How stand I then,
     That have a father kill’d, a mother stain’d,
     Excitements of my reason and my blood,
     And let all sleep?

Is it not clear that he is speculating just as vainly now, and that this question of conscience is but one of his many unconscious excuses for delay?  And, lastly, is it not so that Horatio takes it?  He declines to discuss that unreal question, and answers simply,

It must be shortly known to him from England
What is the issue of the business there.

In other words, ’Enough of this endless procrastination.  What is wanted is not reasons for the deed, but the deed itself.’  What can be more significant?

Perhaps, however, it may be answered:  ’Your explanation of this passage may be correct, and the facts you have mentioned do seem to be fatal to the theory of conscience in its usual form.  But there is another and subtler theory of conscience.  According to it, Hamlet, so far as his explicit consciousness went, was sure that he ought to obey the Ghost; but in the depths of his nature, and unknown to himself, there was a moral repulsion to the deed.  The conventional moral ideas of his time, which he shared with the Ghost, told him plainly that he ought to avenge his father; but a deeper conscience in him, which was in advance of his time, contended with these explicit conventional ideas.  It is because this deeper conscience remains below the surface that he fails to recognise it, and fancies he is hindered by cowardice or sloth or passion or what not; but it emerges into light in that speech to Horatio.  And it is just because he has this nobler moral nature in him that we admire and love him.’

Now I at once admit not only that this view is much more attractive and more truly tragic than the ordinary conscience theory, but that it has more verisimilitude.  But I feel no doubt that it does not answer to Shakespeare’s meaning, and I will simply mention, out of many objections to it, three which seem to be fatal. (a) If it answers to Shakespeare’s meaning, why in the world did he conceal that meaning until the last Act?  The facts adduced above seem to show beyond question that, on the hypothesis, he did so.