learly forms part of those anticipatory sceptical arguments
which Cic. in the first edition had included in his answer to Hortensius,
see Introd. p. 55. The argument probably ran thus: What seems so level as
the sea? Yet it is easy to prove that it is really not level.

4. On this I have nothing to remark.

5. There is nothing distinctive about this which might enable us to
determine its connection with the dialogue. Probably Zeno is the person who
_serius adamavit honores_.

6. The changing aspects of the same thing are pointed to here as
invalidating the evidence of the senses.

7. This passage has the same aim as the last and closely resembles
_Lucullus_ 105.

8. The fact that the eye and hand need such guides shows how untrustworthy
the senses are. A similar argument occurs in _Luc._ 86. _Perpendiculum_ is
a plumb line, _norma_ a mason's square, the word being probably a
corruption of the Greek [Greek: gnomon] (Curt. _Grundz_ p. 169, ed. 3),
_regula_, a rule.

9. The different colours which the same persons show in different
conditions, when young and when old, when sick and when healthy, when sober
and when drunken, are brought forward to prove how little of permanence
there is even in the least fleeting of the objects of sense.

10. _Urinari_ is to dive; for the derivation see Curt. _Grundz_ p. 326. A
diver would be in exactly the position of the fish noticed in _Luc._ 81,
which are unable to see that which lies immediately above them and so
illustrate the narrow limits of the power of vision.

11. Evidently an attempt to prove the sense of smell untrustworthy.
Different people pass different judgments on one and the same odour. The
student will observe that the above extracts formed part of an argument
intended to show the deceptive character of the senses. To these should
probably be added fragm. 32. Fr. 19 shows that the impossibility of
distinguishing eggs one from another, which had been brought forward in the
_Catulus_, was allowed to stand in the second edition, other difficulties
of the kind, such as those connected with the bent oar, the pigeon's neck,
the twins, the impressions of seals (_Luc._ 19, 54), would also appear in
both editions. The result of these assaults on the senses must have been
summed up in the phrase _cuncta dubitanda esse_ which Augustine quotes from
the _Academica Posteriora_ (see fragm. 36).

BOOK III.

12. This forms part of Varro's answer to Cicero, which corresponded i