Let us add a further detail from this picture of the atom, as given in Eddington's Philosophy of Physical Science. Referring to the so-called positron, the positive particle regarded as the polar opposite of the negative electron, he remarks: 'A positron is a hole from which an electron has been removed; it is a bung-hole which would be evened up with its surroundings if an electron were inserted. ... You will see that the physicist allows himself even greater liberty than the sculptor. The sculptor removes material to obtain the form he desires. The physicist goes further and adds material if necessary - an operation which he describes as removing negative material. He fills up a bung-hole, saying he is removing a positron.' Eddington thus shows to what paradoxical ideas the scientist is driven, when with his accustomed forms of thought he ventures into regions where the conditions necessary for such forms no longer exist; and he concludes his remarks with the following caution: 'Once again I would remind you that objective truth is not the point at issue.'