The weakness of hoplites against cavalry?

[Bodeni]

The battle of Platea, according to Herodotus.

The Sicilian expedition, during the Peloponnesian war.

Agesilaus expedition in minor Asia.

I have recently read the work of Herodotus, Thucidydes, and Xeneophon ('Hellenica').

There are many referances about a 'hollow square', similar to the Roman tactic against the Parthians.

Could not hoplites have formed many 'infantry squares', like what the Europeans did during the Napoleon wars?

The general idea is to fight only from one direction at a time, while none of the backs are exposed.

Main problem with the "Infantry square" is that it can only be a couple of men thick. Fine and dandy when you have bayonets and muskets, or when you know your enemy is largely mounted. But a very large majority of battles consist primarily of infantry. A hoplite in the Peloponnesian war for example, was 8 men thick. Combined with its breadth, such a formation makes a schiltron, or square, useless. Another point to note is that hoplites were not as mobile or well drilled in maneuvers as the later Roman soldiers were.

I can't say I know much about Agesilaus' battles, but for the others, the sort of cavalry available would be mostly scouts, skirmishers and messengers. The Hellenic world wouldn't warm to the use of heavy cavalry until the later part of the 4th century BC. Thus the organised, wealthy, well armoured hoplites would carry quite some advantage.