@alexliu,
My apologies alexliu...I didn't notice the quotation marks etc!!!
Setanta has done a great job...I'll do my interpretation too, so you have a couple to look at.
The piece is very ironic and meant to be funny and also quite provocative.
“such as living would assuredly display, I think, if my progress were directed by any particular motive”.
I think he is saying that he denies any soul, or spiritual element, or god.
Remember, he has started by saying that he would like life not to be dependent upon the physical.."the tyranny of matter"...(and the inclusion of books with food and flesh etc. is quite funny) but here, as in the other paragraphs, he goes on to deny the possibility of what he wishes for. That is, he is saying that we are just matter, after all, as he can see no evidence of anything else...
“Married people are not ever tender with each other, you will notice: if they are mutually civil it is much: and physical contacts apart, their relation is that of a very moderate intimacy”.
Again, he is talking about how little tenderness, which he says he desires, there is between humans, and using examples which would, in popular sentiment, have defined tenderness (parental bond, marital bond) to debunk its existence.
He says there is a brief period of tenderness (a truce in what he sees as the ongoing hostility between men and women, and indeed, between all adults) between adults when they are courting, but it does not survive much beyond marriage.
(Do you understand the meaning of "tender" here?
It is used in the sense of:
a. Considerate and protective; solicitous: a tender mother; his tender concern.
b. Characterized by or expressing gentle emotions; loving: a tender glance; a tender ballad.
c. Given to sympathy or sentimentality; soft: a tender heart.)
So, he notes that married people are seldom kind and solicitous of each other, and share little emotional or intellectual intimacy. He says they are intimate only physically (being "intimate" with someone can be used to mean thay have sex, as well as the other meanings of intimacy.)
and very much the same principle which prompts small boys to jeer at a straw-hat out of season induces their elders to send missionaries to the heathen…
This is wonderfully challenging!!
He says that people are naturally xenophobic and intolerant of anyone (or any culture) different from ourselves.
Popular sentiment at the time would have seen being a missionary as a sacred calling, noble in its intent to bring god's truth and civilization to the benighted heathens. (Including the Chinese!)
He delightfully punctures this view by saying it is impelled by the same motives that lead us to be critical of others for such ridiculous things as dressing a little unfashionably.
It's rather a bleak world that he sees for humans.
No meaning or purpose, no love, and no tolerance and critical self-awareness!