diff --git a/history/005_letter_test/src/main/java/com/github/drinkjava2/frog/brain/organ/Eye.java b/history/005_letter_test/src/main/java/com/github/drinkjava2/frog/brain/organ/Eye.java
new file mode 100644
index 0000000..a9c06f2
--- /dev/null
+++ b/history/005_letter_test/src/main/java/com/github/drinkjava2/frog/brain/organ/Eye.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2018 the original author or authors. 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by
+ * applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
+ * OF ANY KIND, either express or implied. See the License for the specific
+ * language governing permissions and limitations under the License.
+ */
+package com.github.drinkjava2.frog.brain.organ;
+
+import com.github.drinkjava2.frog.Frog;
+import com.github.drinkjava2.frog.brain.Cuboid;
+import com.github.drinkjava2.frog.brain.Organ;
+import com.github.drinkjava2.frog.util.ColorUtils;
+import com.github.drinkjava2.frog.util.PixelsUtils;
+
+/**
+ * Eye can only see env material
+ * 
+ * @author Yong Zhu
+ */
+public class Eye extends Organ {// 眼睛是长方体
+	private static final long serialVersionUID = 1L;
+
+	public Eye() {
+		this.shape = new Cuboid(0, 3, 2, 1, 13, 13);
+		this.type = Organ.EYE;
+		this.organName = "Eye";
+		this.allowVary = false;// 不允许变异
+		this.allowBorrow = false;// 不允许借出
+		this.color = ColorUtils.GRAY;
+	}
+
+	/** Clear image on retina */
+	public void seeNothing(Frog f) {// 外界可以直接调用这个方法，清除视网膜图像
+		f.setCuboidVales((Cuboid) shape, false);
+	}
+
+	/**
+	 * Accept a byte[x][y] array, active tubes located on eye's retina
+	 * 
+	 * 接收一个二维数组，激活它视网膜所在的脑空间
+	 */
+	public void seeImage(Frog f, byte[][] pixels) {// 外界可以直接调用这个方法，硬塞一个象素图到视网膜上
+		if (!f.alive)
+			return;
+		int w = pixels.length;
+		int h = pixels[0].length;
+		Cuboid c = (Cuboid) shape;
+
+		// 在视网膜上产生字母像素点阵，即激活这个脑视网膜所在的cells区，然后由器官播种出的脑细胞负责将激活能量转为光子输送、存贮到其它位置
+		for (int px = 0; px < w; px++)
+			for (int py = 0; py < h; py++)
+				if (pixels[px][py] > 0)
+					f.getOrCreateCell(0, c.y + c.ye - px - 1, c.z + py).hasInput = true;
+	}
+
+	public void seeImageWithOffset(Frog f, byte[][] pixels, int xOff, int yOff) {// 外界硬塞一个象素图到视网膜上，并给出偏移量
+		byte[][] newPixels = PixelsUtils.offset(pixels, xOff, yOff);
+		seeImage(f, newPixels);
+	}
+}