therefore to understand the meaning of such an observation statement one must simultaneously execute the gesture, one must somehow point to reality. 

In other words: I can understand the meaning of a "confirmation" only by, and when, comparing it with the facts, thus carrying out that process which is necessary for the verification of all synthetic statements. While in the case of all other synthetic statements determining the meaning is separate from, distinguishable from, determining the truth, in the case of observation statements they coincide, just as in the case of analytic statements. However different therefore "confirmations" are from analytic statements, they have in common that the occasion of understanding them is at the same time that of verifying them: I grasp their meaning at the same time as I grasp their truth. In the case of a confirmation it makes as little sense to ask whether I might be deceived regarding its truth as in the case of a tautology. Both are absolutely valid. However, while the analytic, tautological, statement is empty of content, the observation statement supplies us with the satisfaction of genuine knowledge of reality. 

It has become clear, we may hope, that here everything depends on the characteristic of immediacy which is peculiar to observation statements and to which they owe their value and disvalue; the value of absolute validity, and the disvalue of uselessness as an abiding foundation. 
A misunderstanding of this nature is responsible for most of the unhappy problems of protocol statements with which our enquiry began. If I make the confirmation "Here now blue," this is not the same as the protocol statement "M. S. perceived blue on the nth of April 1934 at such and such a time and such and such a place." The latter statement is a hypothesis and as such always characterized by uncertainty. The latter statement is equivalent to "M. S. made ... (here time and place are to be given) the confirmation 'here now blue.'Ó And that this assertion is not identical with the confirmation occurring in it is clear. In protocol statements there is always mention of perceptions (or they are to be added in thought -- the identity of the perceiving observer is important for a scientific protocol), while they are never mentioned in confirmations. A genuine confirmation cannot be written down, for as soon as I inscribe the demonstratives "here," "now," they lose their meaning. Neither can they be replaced by an indication of time and place, for as soon as one attempts to do this, the result, as we saw, is that