The Non-Mixing of Unlike Things (Deuteronomy 22:9-11).
Unlike things should not be put together as no one could have any idea how they would finally react (compare Leviticus 19:19). By dealing with things individually many problems could be avoided. There is probably underlying this the idea of respect for the distinctions within creation which must not be blurred. There may also be intended a subtle warning against being involved with the Canaanites, and thus mixing unlike with unlike, for they might be compared to grapes against grain (drunkenness against good bread), ass as against an ox bull or sheep (unclean against clean), or linen as opposed to wool (sophistication against tribal decency).
But the fact that we have three examples does suggest that there is an aspect of incompatibility in mind.
‘ You shall not sow your vineyard with two kinds of seed, lest the whole fruit be forfeited (literally ‘be made holy'), the seed which you have sown, and the increase of the vineyard.'
Practically speaking the danger of seeking to grow two things on the same piece of land was that there may not be sufficient sustenance for both, thus both might fail to grow properly. It would therefore be something best avoided. But the reference to ‘making holy' might refer to the produce being seen as Yahweh's and confiscated by the Sanctuary to save it from idolatrous significance, rather than to its just being naturally forfeited through its not growing properly. If this was so it may have been because such mixing was known to have religious significance among the Canaanites and/or the Egyptians, something which Moses and the people could have learned in Egypt. We know from inscriptions that Egypt had nothing against growing trees amidst grain, and that this was practised in sacred gardens. It may therefore have had an idolatrous taint.
It is, however, quite possible that grain and fruit that did not become edible was, with wry humour, spoken of as being ‘made holy', that is, not available for eating, which would then support the first idea.
In the same way Leviticus 19:19 forbids the sowing of two types of seed in a field, presumably together. The folly of this would be that they choked each other and might grow at different rates. Thus harvesting problems would be caused.
But behind it all would seem to be the principle that what was compatible must go with what was compatible, that there be no dissension in creation.
‘ You shall not plough with an ox and an ass together.'
This may well have been because one was ‘clean', and the other was not. To do this would thus be seeming to have a disregard for holiness. Alternately it may have been because of the incompatibility between the two and out of consideration for both. The danger with ploughing with two such different animals in the yoke could be that neither cooperated and that both were uneasy, thus making ploughing difficult. The Arabs did, however, in fact put ox and ass together in the yoke.
On the other hand the aim may have been to prevent a mutual relationship being built up between such unlike animals as they worked together, causing unnecessary distress. Such bonds between disparate animals do occur and would cause great distress on separation. Any way it is looked at the principle appears to have the animals' welfare in mind.
Compare how Leviticus 19:19 forbids bringing two types of animal together for the purpose of breeding. This would indeed produce sterile offspring. But the stress is on the incompatability. It would be unseemly.
‘ You shall not wear a mixed fabric, wool and linen together.'
The form of the word for ‘mixed fabric' demonstrates that it was not native Hebrew but was borrowed from another language and was probably an Egyptian loan word. This may suggest that it had a special type of religious implication. If so such a mixing of cloth might then have had connections with idolatry, the occult and magic and constantly have reminded those who wore it of such idolatry or magic, and may even have made them feel entrapped by such things.
Or it may be that we should remember that linen was what was worn by the priests. It might thus have been seen as having an aura of holiness. It may have been felt that to mix this with common wool was to degrade linen's significance. Others have suggested that it was what prostitutes wore.
But the practical problem with mixing two types of such distinctive cloth was firstly that they might not weave well together, each having different strengths, and secondly that when washed each might react differently thus spoiling the garment (compare the new patch and old garment mentioned by Jesus (Mark 2:21)). That may indeed have been the sole reason for the restriction. Compare again Leviticus 19:19.
But the threefold repetition of examples would suggest that below all the other reasons lay the fact of incompatibility, and the importance of maintaining distinctions, whether for religious, ethical or practical reasons. And it may be that this principle was then to be extended towards ways of living. How shall two walk together except they be agreed?