# 5.2522 explained — Tractatus Logico-Philosophicus

> Chapter companion for Tractatus Logico-Philosophicus by Ludwig Wittgenstein.

## What happens

Wittgenstein introduces a notation for the general term of a formal series, using the expression '[a, x, O'x]' to represent the series a, O'a, O'O'a, ... He explains that this bracketed expression is a variable, where the first term is the beginning of the series, the second is the form of an arbitrary term x, and the third is the form of the term immediately following x.

## Character check-ins

### Mr. Wittgenstein

Introduces notation for the general term of a formal series.

## Key lines

> The general term of the formal series a , O ′ ⁡ a , O ′ ⁡ O ′ ⁡ a ,⁠ ⁠… I write thus: “ [ a , x , O ′ ⁡ x ] ”.

I write the general term of the formal series a, O'a, O'O'a, ... as '[a, x, O'x]'.

_Wittgenstein defines a notation for expressing the general form of a series generated by repeated application of an operation._

> This expression in brackets is a variable. The first term of the expression is the beginning of the formal series, the second the form of an arbitrary term x of the series, and the third the form of that term of the series which immediately follows x.

The bracketed expression is a variable: the first term is the starting point of the series, the second is the pattern of any term x, and the third is the pattern of the term that comes right after x.

_Wittgenstein explains the components of his notation for the formal series._

## Links

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