《老子》‧第二章
天下皆知美之為美，斯惡已；皆知善之為善，斯不善已。故有無相生，難易相成，長短相形，高下相傾，音聲相和，前後相隨。
是以聖人處無為之事，行不言之教。萬物作焉而不辭，生而不有，為而不恃，功成而弗居。夫唯弗居，是以不去。
何謂『矛盾』的呢？ 『此』且『非此』，『彼』又『非彼』一類的『概念』。若問『善』與『惡』是『矛盾』的嗎？假使人世間有『不善不惡』之事或『既善且惡』之行，當然『善‧惡』就不可說是邏輯的『矛盾』。即使沒有『又善又惡』的事件，那『善‧惡』的概念是否就可窮盡一切現象哩！要是存在『無記』之『非善非惡 』的作為，那『善‧惡』依然不可說是邏輯的『矛盾』！！
如果此時舉維基百科裡『文氏圖』解釋用的例子來講︰
在這個例子中，一個集合完全在另一個集合內部。我們說集合A是在世界中能找到的所有的不同類型的奶酪，集合B是在世界中能找到的所有食物。從這個圖中，你可以看出所有奶酪都是食物，但是不是所有食物都是奶酪。進一步的說，集合C（比如說金屬造物）與集合B沒有公共元素（集合的成員），從此我們可以在邏輯上斷言沒有奶酪是金屬造物（或者反過來說）。在形式上，上述的圖可以在數學上解釋為”集合A是集合B的真子集，而集合C和集合B沒有公共元素”。
或解釋為一個三段論
- 所有As是Bs
- 沒有Cs是Bs
- 所以，沒有Cs是As
- 所以，沒有As是Cs。
彷彿通常人們較容易理解這『 ABC 』的關係！？這是為什麼的呢？ ？曾有人說︰人類的大腦是個不設防的城市。說不定那個『大腦』還很容易先入為主，形成『刻板』印象，以至於理念時會自相矛盾而不『自知』。這或許就是一個『判斷』之『健不健全』，所依賴的『理則 』、『證據』以及『價值』之先後次序常常混亂不清，『理性』老是與『感性』衝突的原故吧！！？？
由於在樹莓派上並沒有『 Open NFC 』適合的軟硬體，在此僅引用一張『 NFC Standards 』圖，
就讓我們經由『 nfc 論壇』組織，
What Is NFC?
Near Field Communication (NFC) is a standards-based short-range wireless connectivity technology that makes life easier and more convenient for consumers around the world by making it simpler to make transactions, exchange digital content, and connect electronic devices with a touch. NFC is compatible with hundreds of millions of contactless cards and readers already deployed worldwide.
We invite you to explore the potential for NFC in your life by selecting a topic of interest from the list below.
About the technology
NFC technology enables short-range wireless interaction between consumer electronics, mobile devices, personal computers, electrical appliances, and NFC-compatible tags. Learn more »
What it does
There are seemingly infinite uses for NFC. Interact dynamically with content, set up connections, make a payment, or present a ticket. Explore uses »
……
Our Mission & Goals
Mission
The Near Field Communication Forum was formed to advance the use of Near Field Communication technology by developing specifications, ensuring interoperability among devices and services, and educating the market about NFC technology. Formed in 2004, the Forum’s global member companies, including manufacturers, applications developers, financial services institutions, and others all work together to promote the use of NFC technology in consumer electronics, mobile devices, PCs, and more.
Goals
The goals of the NFC Forum are to:
- Develop standards-based Near Field Communication specifications that define a modular architecture and interoperability parameters for NFC devices and protocols
- Encourage the development of products using NFC Forum specifications
- Work to ensure that products claiming NFC capabilities comply with NFC Forum specifications
- Educate consumers and enterprises globally about NFC
The NFC Forum provides a highly stable framework for extensive application development, seamless interoperable solutions, and security for NFC-enabled transactions. The NFC Forum has organized the efforts of dozens of member organizations by creating Committees and Working Groups.
In June 2006, only 18 months after its founding, the Forum formally outlined the architecture for NFC technology. The Forum has released 16 specifications to date. The specifications provide a “road map” that enables all interested parties to create powerful new consumer-driven products.
View NFC Forum Specifications List
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嘗試進入『派生 nfc 』的大門，
nfcpy 
Python module for near field communication
This documentation covers the ‘trunk‘ version of
nfcpy. Source code, issue tracker and a question/answer section are at
https://launchpad.net/nfcpy.
The nfcpy module implements NFC Forum specifications for wireless short-range data exchange with NFC devices and tags. It is written in Python and aims to provide an easy-to-use yet powerful framework for contactless applications. The software is licensed under the EUPL.
To send a web link to a smartphone:
>>> import nfc, nfc.snep, threading
>>> connected = lambda llc: threading.Thread(target=llc.run).start()
>>> uri = nfc.ndef.Message(nfc.ndef.UriRecord("http://nfcpy.org"))
>>> clf = nfc.ContactlessFrontend('usb')
>>> llc = clf.connect(llcp={'on-connect': connected})
>>> nfc.snep.SnepClient(llc).put(uri)
True
>>> clf.close()
There are also a number of Example Programs that can be used from the command line:
$ examples/beam.py send link http://nfcpy.org
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或可一窺『 NFC 實務』的堂奧。
cd nfc pi@raspberrypi ~
ls nfcpy-0.10.0.tar.gz pi@raspberrypi ~/nfc
sudo apt-get install python-usb pi@raspberrypi ~/nfc
sudo pip install docopt==0.6.1 # 執行驗證 pi@raspberrypi ~/nfc
python examples/tagtool.py show [nfc.clf] searching for reader on path usb [nfc.clf] no reader available on path usb [main] no contactless reader found on usb [main] no contactless reader available # 指定裝置，注意使用者 pi 的讀寫權限 pi@raspberrypi ~/nfc/0.10.0
sudo python examples/tagtool.py --device usb:072f:2200 show [nfc.clf] searching for reader on path usb:072f:2200 [nfc.clf] using ACS ACR122U PN532v1.6 at usb:001:008 ** waiting for a tag ** Type2Tag ID=E0E72711 # 依建議增加 nfc 裝置的 udev 規則 pi@raspberrypi ~/nfc/0.10.0
more /etc/udev/rules.d/nfcdev.rules SUBSYSTEM=="usb", ACTION=="add", ATTRS{idVendor}=="072f", ATTRS{idProduct}=="220 0", GROUP="plugdev" # 重新開機 pi@raspberrypi ~/nfc/0.10.0
python examples/tagtool.py --device usb:072f:2200 show [nfc.clf] searching for reader on path usb:072f:2200 [nfc.clf] using ACS ACR122U PN532v1.6 at usb:001:008 ** waiting for a tag ** Type2Tag ID=E0E72711 pi@raspberrypi ~/nfc/0.10.0
python examples/tagtool.py --device tty:USB0:pn532 show [nfc.clf] searching for reader on path tty:USB0:pn532 [nfc.clf] using PN532v1.6 at /dev/ttyUSB0 ** waiting for a tag ** Type2Tag ID=E0E72711 pi@raspberrypi ~/nfc/0.10.0
ndeftool.py [-h] [-v] [-d] {print,make,pack,split,cat} ...
sudo nfc-list
nfc-list uses libnfc 1.7.1
NFC device: pn532_uart:/dev/ttyUSB0 opened
1 ISO14443A passive target(s) found:
ISO/IEC 14443A (106 kbps) target:
ATQA (SENS_RES): 00 04
UID (NFCID1): e0 e7 27 11
SAK (SEL_RES): 08
pi@raspberrypi ~ $
