Lookup And Reference For Category And Date?

I'm having serious difficulties with getting together a formula for a little bit complicated lookup.

I have 2 tables. In the first table I have categories in the first column (e.g. red, blue, green), in the second column I have dates (DD.MM.YYYY). And in the third column I would like to get the values from the second table.

In the second table I also have categories in the first column, dates in the second column und values in the third.

I would now like to get the values from the second table that coincide with the categories. And in addition the dates should also be equal to the date in the first table OR the date from the second table should be as close as possible but BEFORE the date in the first table.

Example
Table1
Red 07.08.2005 ???

Table 2
Red 18.04.2005 three
Blue 11.06.2005 one
Red 06.08.2005 four

In this example the value that should be looked up is "four".