Problem with Greek language

Question

I am trying to write an essay in Greek and I type Greek characters but it doesn't compile. I have downloaded both greektex and program Babylon but it seems that I can't make them work.

Answer 1

If you have only Greek text, then the following is a good setup for pdflatex:

\documentclass[a4paper]{article}
\usepackage[greek]{babel}
\begin{document}
πάντες ἄνθρωποι τοῦ εἰδέναι ὀρέγονται φύσει. σημεῖον δ᾽ ἡ τῶν αἰσθήσεων ἀγάπησις: 
καὶ γὰρ χωρὶς τῆς χρείας ἀγαπῶνται δι᾽ αὑτάς, καὶ μάλιστα τῶν ἄλλων ἡ διὰ τῶν 
ὀμμάτων. οὐ γὰρ μόνον ἵνα πράττωμεν ἀλλὰ καὶ μηθὲν μέλλοντες πράττειν τὸ ὁρᾶν 
αἱρούμεθα ἀντὶ πάντων ὡς εἰπεῖν τῶν ἄλλων. αἴτιον δ᾽ ὅτι μάλιστα ποιεῖ γνωρίζειν 
ἡμᾶς αὕτη τῶν αἰσθήσεων καὶ πολλὰς δηλοῖ διαφοράς. φύσει μὲν οὖν αἴσθησιν ἔχοντα 
γίγνεται τὰ ζῷα, ἐκ δὲ ταύτης τοῖς μὲν αὐτῶν οὐκ ἐγγίγνεται μνήμη, τοῖς δ᾽ ἐγγίγνεται.
\bigskip
πάντες ἄνθρωποι (\ensureascii{all people})
\end{document}

If, by chance, you need to input Latin characters, you can enclose the word in \ensureascii, as shown above

πάντες ἄνθρωποι (\ensureascii{all people})

Consult the babel documentation if you need other languages,

Older (and obsolete) answer

If you have only Greek text, then the following is a good setup for pdflatex:

\documentclass[a4paper]{article}
\usepackage[LGRx,LGR]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[greek]{babel}
\begin{document}
πάντες ἄνθρωποι τοῦ εἰδέναι ὀρέγονται φύσει. σημεῖον δ᾽ ἡ τῶν αἰσθήσεων ἀγάπησις: 
καὶ γὰρ χωρὶς τῆς χρείας ἀγαπῶνται δι᾽ αὑτάς, καὶ μάλιστα τῶν ἄλλων ἡ διὰ τῶν 
ὀμμάτων. οὐ γὰρ μόνον ἵνα πράττωμεν ἀλλὰ καὶ μηθὲν μέλλοντες πράττειν τὸ ὁρᾶν 
αἱρούμεθα ἀντὶ πάντων ὡς εἰπεῖν τῶν ἄλλων. αἴτιον δ᾽ ὅτι μάλιστα ποιεῖ γνωρίζειν 
ἡμᾶς αὕτη τῶν αἰσθήσεων καὶ πολλὰς δηλοῖ διαφοράς. φύσει μὲν οὖν αἴσθησιν ἔχοντα 
γίγνεται τὰ ζῷα, ἐκ δὲ ταύτης τοῖς μὲν αὐτῶν οὐκ ἐγγίγνεται μνήμη, τοῖς δ᾽ ἐγγίγνεται.
\end{document}

In case you have a TeX distribution that hasn't LGRx, then

\documentclass[a4paper]{article}
\usepackage[LGR]{fontenc}
\usepackage[utf8x]{inputenc}
\usepackage[greek]{babel}

should work; but I recommend updating the TeX system. You realize that LGRx is not available when you get the following error message:

! Package fontenc Error: Encoding file `lgrxenc.def' not found.
(fontenc)                You might have misspelt the name of the encoding.

Of course, the \documentclass line can contain whatever class you prefer.

Answer 2

I likewise do not know exactly what you mean by "it doesn't compile".

Nevertheless, this is what I would do if I wanted to typeset Greek: I would use LuaLaTeX. With LuaLaTeX you could just type greek without any additional packages -- provided that you use a font that contains all the greek symbols (and accents) you are about to use.

For example:

% !TEX TS-program = lualatexmk
\documentclass[11pt, a4paper]{scrartcl}

\usepackage{fontspec}
\setmainfont[Script=Greek, Ligatures=TeX]{Arial Unicode MS}

\begin{document}

πάντες ἄνθρωποι τοῦ εἰδέναι ὀρέγονται φύσει. σημεῖον δ᾽ ἡ τῶν αἰσθήσεων ἀγάπησις: 
καὶ γὰρ χωρὶς τῆς χρείας ἀγαπῶνται δι᾽ αὑτάς, καὶ μάλιστα τῶν ἄλλων ἡ διὰ τῶν 
ὀμμάτων. οὐ γὰρ μόνον ἵνα πράττωμεν ἀλλὰ καὶ μηθὲν μέλλοντες πράττειν τὸ ὁρᾶν 
αἱρούμεθα ἀντὶ πάντων ὡς εἰπεῖν τῶν ἄλλων. αἴτιον δ᾽ ὅτι μάλιστα ποιεῖ γνωρίζειν 
ἡμᾶς αὕτη τῶν αἰσθήσεων καὶ πολλὰς δηλοῖ διαφοράς. φύσει μὲν οὖν αἴσθησιν ἔχοντα 
γίγνεται τὰ ζῷα, ἐκ δὲ ταύτης τοῖς μὲν αὐτῶν οὐκ ἐγγίγνεται μνήμη, τοῖς δ᾽ ἐγγίγνεται.

\end{document}

If you decided that you also need other languages and scripts (English/Latin, Hebrew, Arabic) this all is no problem. Plus: you don't need to learn new syntax or commands if you switch from LaTeX2e to LuaLaTeX.