Preventing C Stack Overflows with __index?

Hello! I am having an issue where I am overriding the table's __index method, but whenever I index the table, I get a C Stack Overflow. Why is this?

local Table = {}
local Metatable = {}

Metatable.__index = function(Key,Value)
    if Value > 10 then
        Table[Key] = 10
    else
        Table[Key] = Value
    end
end